ttl: fix potential go leak for ttl in test

[lcwangchao]

What problem does this PR solve?

Issue Number: close #46948

What is changed and how it works?

In the previous code, the ttlJobManager is created and started in a background goroutine:

tidb/domain/domain.go

Lines 2917 to 2929 in a7e3176

	func (do *Domain) StartTTLJobManager() {
	do.wg.Run(func() {
	defer func() {
	logutil.BgLogger().Info("ttlJobManager exited.")
	}()
	ttlJobManager := ttlworker.NewJobManager(do.ddl.GetID(), do.sysSessionPool, do.store, do.etcdClient, do.ddl.OwnerManager().IsOwner)
	do.ttlJobManager.Store(ttlJobManager)
	ttlJobManager.Start()
	<-do.exit
	}, "ttlJobManager")
	}

It has a probability that if a test runs very fast and domain.Close will be called before do.ttlJobManager.Store(ttlJobManager) . The ttlJobManager will not stop anymore.

In this PR, we just move ttlJobManager's create and start out of the goroutine.

Check List

Tests

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

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

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, YangKeao

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-09-13 10:24:31.446272725 +0000 UTC m=+81037.413860776: ☑️ agreed by hawkingrei.
• 2023-09-13 10:27:52.246041741 +0000 UTC m=+81238.213629791: ☑️ agreed by YangKeao.

[codecov]

Codecov Report

Merging #46953 (665763a) into master (c7f5781) will decrease coverage by 0.4507%.
Report is 16 commits behind head on master.
The diff coverage is 76.0000%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #46953        +/-   ##
================================================
- Coverage   73.2870%   72.8363%   -0.4507%     
================================================
  Files          1331       1352        +21     
  Lines        397358     407243      +9885     
================================================
+ Hits         291212     296621      +5409     
- Misses        87541      92048      +4507     
+ Partials      18605      18574        -31     

Flag	Coverage Δ
integration	28.3850% <15.4285%> (?)
unit	73.5495% <76.0000%> (+0.2624%)	⬆️

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

Components	Coverage Δ
dumpling	54.0444% <ø> (ø)
parser	85.0019% <ø> (ø)
br	48.6139% <100.0000%> (-4.2997%)	⬇️

[hawkingrei]

/test all

[hawkingrei]

/retest

[lcwangchao]

/retest

[hawkingrei]

/retest