Allow client template config block to be parsed when using json config

[ncode]

cat ./debug/config.json
{
  "bind_addr": "0.0.0.0",
  "client": {
    "cni_config_dir": "/etc/nomad/cni.d",
    "cni_path": "/usr/libexec/cni",
    "enabled": true,
    "max_dynamic_port": 20010,
    "min_dynamic_port": 20000,
    "servers": [
      "nomad-server-001.internal"
    ],
    "template": {
      "wait": {
        "max": "15s",
        "min": "5s"
      },
      "wait_bounds": {
        "max": "15s",
        "min": "5s"
      }
    }
  },
  "consul": {
    "address": "consul.internal:8500"
  },
  "data_dir": "/opt/nomad/data",
  "datacenter": "dc1",
  "name": "nomad-client-001",
  "telemetry": {
    "collection_interval": "1s",
    "disable_hostname": true,
    "prometheus_metrics": true,
    "publish_allocation_metrics": true,
    "publish_node_metrics": true
  },
  "vault": {
    "address": "https://vault.services.internal",
    "enabled": true
  }
}

Btw I think the artifacts block will have the same problem

Fixes #24001

[tgross]

Hi @ncode! There should be tests in config_parse_test.go that will exercise this code. We should make sure this bug fix is covered by those tests.

Also, can you run make cl to add a changelog item for the bug fix?

[ncode]

@tgross cool, I'm going to work on that today!

[tgross]

Hi @ncode! Test looks great but we need to get CI passing before we can merge. If you hclfmt that one file, that should allow checks to pass and tests to run.

[tgross]

LGTM!

This will ship in the upcoming Nomad 1.9, with backports to Nomad Enterprise. Thanks again @ncode!