sessionctx: fix null max value to leading wrong warning

[hawkingrei]

What problem does this PR solve?

Issue Number: close #57889

Problem Summary:

What changed and how does it work?

forget to set max value, it will judge wrongly when to verify value.

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.

fix null max value to leading wrong warning with tidb_gogc_tuner_max_value。tidb_gogc_tuner_min_value

修复 tidb_gogc_tuner_max_value/tidb_gogc_tuner_min_value 因为 空的 max value 导致错误的warning信息

[hawkingrei]

/check-issue-triage-complete

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.4634%. Comparing base (6434ca4) to head (6db1bcd).
Report is 16 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #57898        +/-   ##
================================================
+ Coverage   72.8734%   73.4634%   +0.5899%     
================================================
  Files          1677       1679         +2     
  Lines        464634     465719      +1085     
================================================
+ Hits         338595     342133      +3538     
+ Misses       105152     102819      -2333     
+ Partials      20887      20767       -120     

Flag	Coverage Δ
integration	43.3882% <100.0000%> (?)
unit	72.3889% <100.0000%> (+0.1138%)	⬆️

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	45.1492% <ø> (-0.5676%)	⬇️

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-12-02 18:25:03.451271778 +0000 UTC m=+1092891.070926291: ☑️ agreed by winoros.
• 2024-12-03 02:09:09.972902598 +0000 UTC m=+1120737.592557114: ☑️ agreed by xhebox.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: winoros, xhebox, yudongusa

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [winoros,xhebox]
• pkg/sessionctx/variable/OWNERS [yudongusa]

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[hawkingrei]

/retest

[hawkingrei]

/cherrypick release-7.5
/cherrypick release-8.1
/cherrypick release-8.5

[ti-chi-bot]

@hawkingrei: new pull request created to branch release-7.5: #57933.

In response to this:

/cherrypick release-7.5
/cherrypick release-8.1
/cherrypick release-8.5

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

@hawkingrei: new pull request created to branch release-8.1: #57934.

In response to this:

/cherrypick release-7.5
/cherrypick release-8.1
/cherrypick release-8.5

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

@hawkingrei: new pull request created to branch release-8.5: #57935.

In response to this:

/cherrypick release-7.5
/cherrypick release-8.1
/cherrypick release-8.5

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.