[close #128] Fix TestClientErrNoPendingRegion

[pingyu]

Signed-off-by: pingyu yuping@pingcap.com

What problem does this PR solve?

Issue Number: close #128

Problem Description: clientSuite.TestClientErrNoPendingRegion is not stable.

What is changed and how does it work?

Make test cases in clientSuite be serial.
Move baseAllocatedID to be acquired before EventFeed goroutine to ensure the correctness of base value.

Note that I'm not sure this PR will fix the issue. Although I re-run the CI and all of them are successful. If the failure happen again, reopen the issue.

Code changes

Check List for Tests

This PR has been tested by at least one of the following methods:

• Unit test

Side effects

Related changes

[codecov]

Codecov Report

Merging #127 (c75a763) into main (b3c6c9b) will decrease coverage by 0.0813%.
The diff coverage is n/a.

❗ Current head c75a763 differs from pull request most recent head 104d12e. Consider uploading reports for the commit 104d12e to get more accurate results

@@               Coverage Diff                @@
##               main       #127        +/-   ##
================================================
- Coverage   59.4629%   59.3815%   -0.0814%     
================================================
  Files           167        167                
  Lines         13294      13324        +30     
================================================
+ Hits           7905       7912         +7     
- Misses         4811       4834        +23     
  Partials        578        578                

Flag	Coverage Δ
cdc	59.3815% <ø> (-0.0814%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cdc/pkg/retry/retry_with_opt.go	90.9090% <0.0000%> (-4.5455%)	⬇️
cdc/cdc/kv/client.go	84.2029% <0.0000%> (-2.1740%)	⬇️
cdc/cdc/http_router.go	81.4814% <0.0000%> (-0.8715%)	⬇️