[WIP] executor: let fetchLoopUnionWithOrderBy support without limit

[Defined2014]

What problem does this PR solve?

Issue Number: close #xxx

Problem Summary:

What is changed and how it works?

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

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None

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This pull-request has been approved by: winoros

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[LGTM Timeline notifier]

Timeline:

• 2023-06-06 09:28:10.111633646 +0000 UTC m=+340476.384606431: ☑️ agreed by winoros.

[winoros]

merged in #43881