statistics: fix invaild asnyc_merge_global_stats

[hawkingrei]

What problem does this PR solve?

Issue Number: close #49041

Problem Summary:

What changed and how does it work?

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

[hawkingrei]

/check-issue-triage-complete

[codecov]

Codecov Report

Merging #49042 (a689ce1) into master (f39e9bf) will increase coverage by 1.5275%.
Report is 5 commits behind head on master.
The diff coverage is 100.0000%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #49042        +/-   ##
================================================
+ Coverage   70.9922%   72.5198%   +1.5275%     
================================================
  Files          1368       1391        +23     
  Lines        403975     410969      +6994     
================================================
+ Hits         286791     298034     +11243     
+ Misses        97214      94126      -3088     
+ Partials      19970      18809      -1161     

Flag	Coverage Δ
integration	43.6987% <100.0000%> (?)
unit	70.9925% <ø> (+0.0002%)	⬆️

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

Components	Coverage Δ
dumpling	53.9663% <ø> (ø)
parser	∅ <ø> (∅)
br	48.3541% <ø> (-4.6181%)	⬇️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hi-rustin, winoros

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• OWNERS [hi-rustin,winoros]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-11-30 08:17:47.050544201 +0000 UTC m=+1083495.715770396: ☑️ agreed by hi-rustin.
• 2023-11-30 09:03:06.865374056 +0000 UTC m=+1086215.530600251: ☑️ agreed by winoros.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #49060.