branch-4.1: [fix](eager-agg) null-to-non-null safety check and remove redundant normalize calls in eager aggregation

[englefly]

What problem does this PR solve?

pick part of #64820

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:

Release note

None

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

[hello-stephen]

Thank you for your contribution to Apache Doris.
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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.
3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[morrySnow]

run buildall

[hello-stephen]

FE Regression Coverage Report

Increment line coverage 0.86% (7/817) 🎉
Increment coverage report
Complete coverage report

[hello-stephen]

[branch41-macos13-runner-retirement]

The BE UT (macOS) job is blocked by a shared workflow issue, not this PR:

• job 90482850046 has been queued since 2026-07-29 04:37 UTC
• it requests the retired macos-13 image and has no runner assignment
• GitHub retired that label on December 4, 2025

Draft PR #66248 switches branch-4.1 to the supported Intel label macos-15-intel, preserving the existing x86_64 third-party package and JAVA_HOME_17_X64. Its own macOS job 90720706740 was assigned a GitHub-hosted Intel runner immediately and is currently in progress.

After #66248 merges, this PR's macOS check still needs to be retriggered and reach a terminal result.