br: fix flaky test TestConcurrentLock

[YuJuncen]

What problem does this PR solve?

Issue Number: ref #56523

Problem Summary:
The test case TestConcurrentLock isn't stable enough.

What changed and how does it work?

Make it more stable by stronger syncing.

# go test -count 2000 -run '^TestConcurrentLock$' github.com/pingcap/tidb/br/pkg/storage
ok      github.com/pingcap/tidb/br/pkg/storage  9.397s

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  It is a test.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[tiprow]

Hi @YuJuncen. Thanks for your PR.

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[codecov]

Codecov Report

Attention: Patch coverage is 35.71429% with 9 lines in your changes missing coverage. Please review.

Project coverage is 74.7237%. Comparing base (91c14a4) to head (2758b86).
Report is 16 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #57591        +/-   ##
================================================
+ Coverage   72.8590%   74.7237%   +1.8646%     
================================================
  Files          1676       1721        +45     
  Lines        463653     474401     +10748     
================================================
+ Hits         337813     354490     +16677     
+ Misses       104979      97710      -7269     
- Partials      20861      22201      +1340     

Flag	Coverage Δ
integration	49.1900% <35.7142%> (?)

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

Components	Coverage Δ
dumpling	52.7673% <ø> (ø)
parser	∅ <ø> (∅)
br	60.5770% <35.7142%> (+15.1265%)	⬆️

---- 🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles

[Tristan1900]

LGTM!

[Tristan1900]

should we close this baseFD in the Close method?

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Tristan1900
Once this PR has been reviewed and has the lgtm label, please ask for approval from yujuncen, ensuring that each of them provides their approval before proceeding. For more information see the Code Review Process.

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Needs approval from an approver in each of these files:

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[ti-chi-bot]

@Tristan1900: adding LGTM is restricted to approvers and reviewers in OWNERS files.

In response to this:

LGTM!

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[YuJuncen]

/test unit-test

[ti-chi-bot]

@YuJuncen: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/check_dev_2	2758b86	link	true	/test check-dev2
idc-jenkins-ci-tidb/unit-test	2758b86	link	true	/test unit-test
pull-br-integration-test	2758b86	link	true	/test pull-br-integration-test

Full PR test history. Your PR dashboard.

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