fix: [2.5] Make controller wait checker worker quit (#42704)

[congqixia]

Cherry-pick from master
pr: #42704
Related to #42702

This patch add wait logic for CheckerController
Nil check already exists due to code branching

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: congqixia

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• internal/querycoordv2/checkers/OWNERS [congqixia]

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[sre-ci-robot]

[INFO] PR Label Summary by Default
[SUCCESS] PR #42704 merged to master

• Title: fix: Make controller wait checker worker quit and add nil protection
• Link: fix: Make controller wait checker worker quit and add nil protection #42704

[WARNING] Milestone not set

• PR: fix: [2.5] Make controller wait checker worker quit (#42704) #42726
• Title: fix: [2.5] Make controller wait checker worker quit (fix: Make controller wait checker worker quit and add nil protection #42704)
  Please set a milestone for better release tracking

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/set-milestone 2.5.0

Use /refresh-label to update related check and label manually

[congqixia]

/refresh-label

[sre-ci-robot]

[INFO] PR Label Summary by Refresh-Label

• Title: fix: [2.5] Make controller wait checker worker quit (fix: Make controller wait checker worker quit and add nil protection #42704)
• Target: 2.5
• Labels: kind/bug, size/XS, approved, dco-passed, do-not-merge/need-milestone

[SUCCESS] PR #42704 merged to master

• Title: fix: Make controller wait checker worker quit and add nil protection
• Link: fix: Make controller wait checker worker quit and add nil protection #42704

Use /refresh-label to update related check and label manually

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.64%. Comparing base (01d408e) to head (ea6fd31).
Report is 2 commits behind head on 2.5.

Additional details and impacted files

@@             Coverage Diff             @@
##              2.5   #42726       +/-   ##
===========================================
+ Coverage   70.70%   80.64%    +9.94%     
===========================================
  Files         311     1431     +1120     
  Lines       30005   206513   +176508     
===========================================
+ Hits        21214   166549   +145335     
- Misses       8791    34093    +25302     
- Partials        0     5871     +5871     

Components	Coverage Δ
Client	79.42% <ø> (∅)
Core	70.70% <ø> (ø)
Go	82.60% <100.00%> (∅)

Files with missing lines	Coverage Δ
internal/querycoordv2/checkers/controller.go	96.52% <100.00%> (ø)

... and 1119 files with indirect coverage changes

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