statistics: BinarySearchRemoveVal should use decoded val instead of encoded

[winoros]

What problem does this PR solve?

Issue Number: close #59130

Problem Summary:

What changed and how does it work?

The function used the wrong val as its parameter.
As a result, when the column is not string type. The function BinaryRemoveVal actually removes nothing.

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.

修复合并全局统计信息时，直方图构造结果可能变大的问题
Fix the issue that the global histogram might be larger than expected when merging partition table's global statistics.

[winoros]

The RemoveVals is actually the wrong one.
But, now that it is only used in stats v1.
I decide not to change it.

[AilinKid]

decide to remove it?

[codecov]

Codecov Report

Attention: Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.

Project coverage is 73.8625%. Comparing base (837b1f5) to head (728689e).
Report is 12 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #59131        +/-   ##
================================================
+ Coverage   73.0925%   73.8625%   +0.7700%     
================================================
  Files          1684       1714        +30     
  Lines        466350     476320      +9970     
================================================
+ Hits         340867     351822     +10955     
+ Misses       104548     102858      -1690     
- Partials      20935      21640       +705     

Flag	Coverage Δ
integration	45.8695% <66.6666%> (?)
unit	72.4376% <77.7777%> (+0.1514%)	⬆️

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

Components	Coverage Δ
dumpling	52.6910% <ø> (ø)
parser	∅ <ø> (∅)
br	45.3462% <ø> (+0.0258%)	⬆️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• pkg/statistics/OWNERS [AilinKid,hawkingrei]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-01-22 13:04:28.694274574 +0000 UTC m=+272396.025193978: ☑️ agreed by hawkingrei.
• 2025-01-23 02:23:31.766759302 +0000 UTC m=+320339.097678707: ☑️ agreed by AilinKid.

[winoros]

/retest

[winoros]

/retest

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #59161.