And remove unnecessary functions. This is done in preparation for
properly locking when updating tags.

Some global variables are patched to shorter values in these tests. But the goroutines that read
them can outlive the test because nothing waited for them to exit.

This commit adds a Wait() method to the routine manager, so that tests can wait for the goroutines
to exit. This prevents the data race because the 'reset to original value' can happen
after all other goroutines have stopped.

The LogOutput io.Writer used by TestAgent must allow concurrent reads and writes, and a
bytes.Buffer does not allow this. The bytes.Buffer must be wrapped with a lock to make this safe.

The dnsConfig pulled from the atomic.Value is a pointer, so modifying it in place
creates a data race. Use the exported ReloadConfig interface instead.

The test was modifying a pointer to a struct that had been passed to
another goroutine. Instead create a new struct to modify.

```
WARNING: DATA RACE
Write at 0x00c01407c3c0 by goroutine 832:
  github.com/hashicorp/consul/agent.TestServiceManager_PersistService_API()
      /home/daniel/pers/code/consul/agent/service_manager_test.go:446 +0x1d86
  testing.tRunner()
      /usr/lib/go/src/testing/testing.go:1193 +0x202

Previous read at 0x00c01407c3c0 by goroutine 938:
  reflect.typedmemmove()
      /usr/lib/go/src/runtime/mbarrier.go:177 +0x0
  reflect.Value.Set()
      /usr/lib/go/src/reflect/value.go:1569 +0x13b
  github.com/mitchellh/copystructure.(*walker).Primitive()
      /home/daniel/go/pkg/mod/github.com/mitchellh/copystructure@v1.0.0/copystructure.go:289 +0x190
  github.com/mitchellh/reflectwalk.walkPrimitive()
      /home/daniel/go/pkg/mod/github.com/mitchellh/reflectwalk@v1.0.1/reflectwalk.go:252 +0x31b
  github.com/mitchellh/reflectwalk.walk()
      /home/daniel/go/pkg/mod/github.com/mitchellh/reflectwalk@v1.0.1/reflectwalk.go:179 +0x24d
  github.com/mitchellh/reflectwalk.walkStruct()
      /home/daniel/go/pkg/mod/github.com/mitchellh/reflectwalk@v1.0.1/reflectwalk.go:386 +0x4ec
  github.com/mitchellh/reflectwalk.walk()
      /home/daniel/go/pkg/mod/github.com/mitchellh/reflectwalk@v1.0.1/reflectwalk.go:188 +0x656
  github.com/mitchellh/reflectwalk.walkStruct()
      /home/daniel/go/pkg/mod/github.com/mitchellh/reflectwalk@v1.0.1/reflectwalk.go:386 +0x4ec
  github.com/mitchellh/reflectwalk.walk()
      /home/daniel/go/pkg/mod/github.com/mitchellh/reflectwalk@v1.0.1/reflectwalk.go:188 +0x656
  github.com/mitchellh/reflectwalk.Walk()
      /home/daniel/go/pkg/mod/github.com/mitchellh/reflectwalk@v1.0.1/reflectwalk.go:92 +0x164
  github.com/mitchellh/copystructure.Config.Copy()
      /home/daniel/go/pkg/mod/github.com/mitchellh/copystructure@v1.0.0/copystructure.go:69 +0xe7
  github.com/mitchellh/copystructure.Copy()
      /home/daniel/go/pkg/mod/github.com/mitchellh/copystructure@v1.0.0/copystructure.go:13 +0x84
  github.com/hashicorp/consul/agent.mergeServiceConfig()
      /home/daniel/pers/code/consul/agent/service_manager.go:362 +0x56
  github.com/hashicorp/consul/agent.(*serviceConfigWatch).handleUpdate()
      /home/daniel/pers/code/consul/agent/service_manager.go:279 +0x250
  github.com/hashicorp/consul/agent.(*serviceConfigWatch).runWatch()
      /home/daniel/pers/code/consul/agent/service_manager.go:246 +0x2d4

Goroutine 832 (running) created at:
  testing.(*T).Run()
      /usr/lib/go/src/testing/testing.go:1238 +0x5d7
  testing.runTests.func1()
      /usr/lib/go/src/testing/testing.go:1511 +0xa6
  testing.tRunner()
      /usr/lib/go/src/testing/testing.go:1193 +0x202
  testing.runTests()
      /usr/lib/go/src/testing/testing.go:1509 +0x612
  testing.(*M).Run()
      /usr/lib/go/src/testing/testing.go:1417 +0x3b3
  main.main()
      _testmain.go:1181 +0x236

Goroutine 938 (running) created at:
  github.com/hashicorp/consul/agent.(*serviceConfigWatch).start()
      /home/daniel/pers/code/consul/agent/service_manager.go:223 +0x4e4
  github.com/hashicorp/consul/agent.(*ServiceManager).AddService()
      /home/daniel/pers/code/consul/agent/service_manager.go:98 +0x344
  github.com/hashicorp/consul/agent.(*Agent).addServiceLocked()
      /home/daniel/pers/code/consul/agent/agent.go:1942 +0x2e4
  github.com/hashicorp/consul/agent.(*Agent).AddService()
      /home/daniel/pers/code/consul/agent/agent.go:1929 +0x337
  github.com/hashicorp/consul/agent.TestServiceManager_PersistService_API()
      /home/daniel/pers/code/consul/agent/service_manager_test.go:400 +0x17c4
  testing.tRunner()
      /usr/lib/go/src/testing/testing.go:1193 +0x202

```

So that the tests in command can use the consul binary

To pick up data race fixes

By setting the hash when we create the policy.

```
WARNING: DATA RACE
Read at 0x00c0028b4b10 by goroutine 1182:
  github.com/hashicorp/consul/agent/structs.(*ACLPolicy).SetHash()
      /home/daniel/pers/code/consul/agent/structs/acl.go:701 +0x40d
  github.com/hashicorp/consul/agent/structs.ACLPolicies.resolveWithCache()
      /home/daniel/pers/code/consul/agent/structs/acl.go:779 +0xfe
  github.com/hashicorp/consul/agent/structs.ACLPolicies.Compile()
      /home/daniel/pers/code/consul/agent/structs/acl.go:809 +0xf1
  github.com/hashicorp/consul/agent/consul.(*ACLResolver).ResolveTokenToIdentityAndAuthorizer()
      /home/daniel/pers/code/consul/agent/consul/acl.go:1226 +0x6ef
  github.com/hashicorp/consul/agent/consul.resolveTokenAsync()
      /home/daniel/pers/code/consul/agent/consul/acl_test.go:66 +0x5c

Previous write at 0x00c0028b4b10 by goroutine 1509:
  github.com/hashicorp/consul/agent/structs.(*ACLPolicy).SetHash()
      /home/daniel/pers/code/consul/agent/structs/acl.go:730 +0x3a8
  github.com/hashicorp/consul/agent/structs.ACLPolicies.resolveWithCache()
      /home/daniel/pers/code/consul/agent/structs/acl.go:779 +0xfe
  github.com/hashicorp/consul/agent/structs.ACLPolicies.Compile()
      /home/daniel/pers/code/consul/agent/structs/acl.go:809 +0xf1
  github.com/hashicorp/consul/agent/consul.(*ACLResolver).ResolveTokenToIdentityAndAuthorizer()
      /home/daniel/pers/code/consul/agent/consul/acl.go:1226 +0x6ef
  github.com/hashicorp/consul/agent/consul.resolveTokenAsync()
      /home/daniel/pers/code/consul/agent/consul/acl_test.go:66 +0x5c

Goroutine 1182 (running) created at:
  github.com/hashicorp/consul/agent/consul.TestACLResolver_Client.func4()
      /home/daniel/pers/code/consul/agent/consul/acl_test.go:1669 +0x459
  testing.tRunner()
      /usr/lib/go/src/testing/testing.go:1193 +0x202

Goroutine 1509 (running) created at:
  github.com/hashicorp/consul/agent/consul.TestACLResolver_Client.func4()
      /home/daniel/pers/code/consul/agent/consul/acl_test.go:1668 +0x415
  testing.tRunner()
      /usr/lib/go/src/testing/testing.go:1193 +0x202
```

This test is super racy, and we already have test coverage for this
functionality in the agent/cache package with TestCacheThrottle.

Instead of spending time rewriting this test, let's remove it.

```
WARNING: DATA RACE
Read at 0x00c01de410fc by goroutine 735:
  github.com/hashicorp/consul/agent.TestCacheRateLimit.func1()
      /home/daniel/pers/code/consul/agent/agent_test.go:1024 +0x9af
  github.com/hashicorp/consul/testrpc.WaitForTestAgent()
      /home/daniel/pers/code/consul/testrpc/wait.go:99 +0x209
  github.com/hashicorp/consul/agent.TestCacheRateLimit.func1()
      /home/daniel/pers/code/consul/agent/agent_test.go:966 +0x1ad
  testing.tRunner()
      /usr/lib/go/src/testing/testing.go:1193 +0x202

Previous write at 0x00c01de410fc by goroutine 605:
  github.com/hashicorp/consul/agent.TestCacheRateLimit.func1.2()
      /home/daniel/pers/code/consul/agent/agent_test.go:998 +0xe9

Goroutine 735 (running) created at:
  testing.(*T).Run()
      /usr/lib/go/src/testing/testing.go:1238 +0x5d7
  github.com/hashicorp/consul/agent.TestCacheRateLimit()
      /home/daniel/pers/code/consul/agent/agent_test.go:961 +0x375
  testing.tRunner()
      /usr/lib/go/src/testing/testing.go:1193 +0x202

Goroutine 605 (finished) created at:
  github.com/hashicorp/consul/agent.TestCacheRateLimit.func1()
      /home/daniel/pers/code/consul/agent/agent_test.go:1022 +0x91e
  github.com/hashicorp/consul/testrpc.WaitForTestAgent()
      /home/daniel/pers/code/consul/testrpc/wait.go:99 +0x209
  github.com/hashicorp/consul/agent.TestCacheRateLimit.func1()
      /home/daniel/pers/code/consul/agent/agent_test.go:966 +0x1ad
  testing.tRunner()
      /usr/lib/go/src/testing/testing.go:1193 +0x202
```