statistics: move MergePartTopN2GlobalTopN into handle/globalstats (#47901)

[ti-chi-bot]

This is an automated cherry-pick of #47901

What problem does this PR solve?

Issue Number: ref #46905

Problem Summary:

What is changed and how it works?

We find it just use 100+ MB memory when to merge global topn without the largest number of partition. so for speeding up the merge-topn, we need to add more data structures such as bloomfilter. so we need to move the MergePartTopN2GlobalTopN into handle/globalstats.

just move the code. not change logical.

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

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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 [hawkingrei,hi-rustin]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-10-23 04:35:57.478349027 +0000 UTC m=+2236555.065459174: ☑️ agreed by hi-rustin.
• 2023-10-23 09:10:37.622783812 +0000 UTC m=+2253035.209893942: ☑️ agreed by hawkingrei.