branch-4.1: [chore](ci) Disable macOS BE UT workflow

[hello-stephen]

What problem does this PR solve?

Related PR: #66248

Problem Summary:

The branch-4.1 macOS BE UT workflow still uses the retired macos-13 GitHub-hosted runner. Recent branch pushes repeatedly created runs that were cancelled without producing useful validation. Migrating this old branch to a current macOS image has also required broad product and test changes, while the migration canary remains failing.

Remove the branch-4.1 macOS BE UT workflow instead of carrying those compatibility changes into the release branch. Linux BE UT and the existing branch validation pipelines are unchanged.

Release note

None

Check List (For Author)

• Test

  • No need to test or manual test. Explain why:
    • No code files have been changed. The deleted workflow is the behavior being removed.

• Behavior changed:

  • Yes. branch-4.1 pushes and schedules no longer start BE UT (macOS).

• Does this need documentation?

  • No.

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?

[hello-stephen]

skip buildall