[Feature](scan) add variable adjust_tablet_reader_batch_size_by_limit

[BiteTheDDDDt]

What problem does this PR solve?

after #22240, we do not push limit to tablet reader.
but sometime the row data is big, so we need use limit to scan less data.

adjust_tablet_reader_batch_size_by_limit=false;

• ScanRows: sum 16.32K (16320), avg 16.32K (16320), max 16.32K (16320), min 16.32K (16320)
  adjust_tablet_reader_batch_size_by_limit=true;
• ScanRows: sum 200, avg 200, max 200, min 200

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[Thearas]

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Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
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4. Which code was refactored and why was this part of the code refactored?
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[BiteTheDDDDt]

run buildall

[Copilot]

Pull request overview

This PR introduces a new session/query option to optionally size the OLAP tablet reader’s batch size based on the query LIMIT, aiming to reduce scan work for queries with small limits (especially when rows are wide).

Changes:

• Added adjust_tablet_reader_batch_size_by_limit to TQueryOptions (Thrift) and to FE session variables (forwarded to BE).
• Added a RuntimeState accessor for the new option in BE.
• Updated OlapScanner::prepare() to optionally set tablet reader batch size to min(batch_size, limit) when enabled.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
gensrc/thrift/PaloInternalService.thrift	Adds a new optional TQueryOptions boolean field to carry the flag from FE to BE.
fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java	Defines the session variable and forwards it into TQueryOptions via toThrift().
be/src/runtime/runtime_state.h	Adds a helper to read the new option from TQueryOptions safely.
be/src/vec/exec/scan/olap_scanner.cpp	Applies the option by adjusting BlockReader batch size based on scanner limit.

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[hello-stephen]

Cloud UT Coverage Report

Increment line coverage 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	79.34% (1797/2265)
Line Coverage	64.80% (32202/49698)
Region Coverage	65.62% (16109/24550)
Branch Coverage	56.13% (8585/15294)

[hello-stephen]

BE Regression && UT Coverage Report

Increment line coverage 55.56% (5/9) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	71.56% (26176/36577)
Line Coverage	54.35% (274452/505015)
Region Coverage	51.71% (228489/441893)
Branch Coverage	53.02% (98103/185014)

[hello-stephen]

FE Regression Coverage Report

Increment line coverage 100.00% (2/2) 🎉
Increment coverage report
Complete coverage report