statistics: update the global stats correctly after truncate a partition

[Rustin170506]

What problem does this PR solve?

Issue Number: close #39681

Problem Summary:

What changed and how does it work?

• Relocated truncate partition logic to truncate_partition.go.
• Updated the global stats correctly, updated the count, and modify_count for the global table.
• Added test case for truncating one partition and multiple partitions.
• Fixed the broken old test case for global stats.

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 TiDB global stats meta update issue after truncating tables

[codecov]

Codecov Report

Merging #49362 (8f52893) into master (0b39f99) will increase coverage by 0.6738%.
Report is 20 commits behind head on master.
The diff coverage is 0.0000%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #49362        +/-   ##
================================================
+ Coverage   71.0491%   71.7229%   +0.6738%     
================================================
  Files          1368       1415        +47     
  Lines        401712     418955     +17243     
================================================
+ Hits         285413     300487     +15074     
- Misses        96443      99629      +3186     
+ Partials      19856      18839      -1017     

Flag	Coverage Δ
integration	43.9467% <0.0000%> (?)
unit	71.0495% <ø> (+0.0003%)	⬆️

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Components	Coverage Δ
dumpling	53.9663% <ø> (ø)
parser	∅ <ø> (∅)
br	47.7924% <ø> (-5.1010%)	⬇️

[Rustin170506]

🔢 Self-check

[Rustin170506]

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[Rustin170506]

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-12-13 04:04:37.668472402 +0000 UTC m=+415368.705699329: ☑️ agreed by hawkingrei.
• 2023-12-13 07:16:05.994617208 +0000 UTC m=+426857.031844135: ☑️ agreed by qw4990.