test: fix data conflict in TestCursorWillBlockMinStartTS

[YangKeao]

What problem does this PR solve?

Issue Number: close #55227

Problem Summary:

There was a data conflict in the test, because the MemTracker is pre-allocated in the cache of StatementContext. If the StatementContext is re-used, the mem tracker will be cleaned..

What changed and how does it work?

Add a ServerStatusCursorExists flag. It makes sure the StatementContext will not be re-used.

Check List

Tests

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

  • I checked and no code files have been changed.

Release note

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

None

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Project coverage is 67.1137%. Comparing base (b066365) to head (a4e25dc).
Report is 1 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #55326        +/-   ##
================================================
- Coverage   74.7027%   67.1137%   -7.5890%     
================================================
  Files          1570       1570                
  Lines        364767     435632     +70865     
================================================
+ Hits         272491     292369     +19878     
- Misses        72509     122972     +50463     
- Partials      19767      20291       +524     

Flag	Coverage Δ
integration	26.3721% <0.0000%> (?)

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

Components	Coverage Δ
dumpling	55.1894% <ø> (ø)
parser	∅ <ø> (∅)
br	48.2506% <ø> (+0.6329%)	⬆️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-09 06:54:23.148110461 +0000 UTC m=+594193.015209550: ☑️ agreed by hawkingrei.
• 2024-08-09 07:45:17.634067508 +0000 UTC m=+597247.501166596: ☑️ agreed by lcwangchao.