statistics: handle the prune mode correctly in the refresher

[Rustin170506]

What problem does this PR solve?

Issue Number: close #57168

Problem Summary:

What changed and how does it work?

When checking the prune mode, we need to ensure that we have loaded the latest variable value. However, directly using the system session pool does not work, as it requires manual updates to obtain the latest global variable value.

In this PR, I utilized the session context from the caller that has already updated the session, allowing us to correctly retrieve the prune mode.

For earlier versions of TiDB, this issue did not occur because we did not use this session to retrieve the global variable in those versions.

Additionally, I added a test case for the queue to verify the handling of DML changes for partitioned tables.

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.

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.2470%. Comparing base (538839b) to head (e0ab534).
Report is 20 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #57096         +/-   ##
=================================================
- Coverage   73.2121%   57.2470%   -15.9651%     
=================================================
  Files          1652       1809        +157     
  Lines        456143     653936     +197793     
=================================================
+ Hits         333952     374359      +40407     
- Misses       101669     254719     +153050     
- Partials      20522      24858       +4336     

Flag	Coverage Δ
integration	39.0066% <0.0000%> (?)
unit	72.9999% <100.0000%> (+0.5109%)	⬆️

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

Components	Coverage Δ
dumpling	52.9478% <ø> (ø)
parser	∅ <ø> (∅)
br	52.4788% <ø> (+6.4909%)	⬆️

[wuhuizuo]

/retest

[Rustin170506]

🔢 Self-check (PR reviewed by myself and ready for feedback.)

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, qw4990

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• pkg/statistics/OWNERS [AilinKid,qw4990]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-11-05 09:27:07.08151802 +0000 UTC m=+946739.920673563: ☑️ agreed by qw4990.
• 2024-11-05 10:17:03.869450214 +0000 UTC m=+949736.708605762: ☑️ agreed by AilinKid.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #57169.