planner, executor: split the range for unsigned pk of partition table when limit is used (#40313)

[ti-chi-bot]

This is an automated cherry-pick of #40313

What problem does this PR solve?

Issue Number: close #40309

Problem Summary:

We ignored the KeepOrder flag for the partition table since it actually doesn't need the request to be returned in order.

But we use the KeepOrder flag to split the signed range and unsigned range for unsigned pk since the tikv stores unsigned part at the front of the signed part.

What is changed and how it works?

Set the KeepOrder flag.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

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]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• fzzf678
• qw4990

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[wuhuizuo]

/hold high priority for trunk branch

[ti-chi-bot]

/unhold

[qw4990]

/test build
/test check_dev

[ti-chi-bot]

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[qw4990]

/test all

[qw4990]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: fcb7ddc