[fix](regression) Fetch streaming job metrics from master FE

[JNSimba]

What problem does this PR solve?

Issue Number: None

Related PR: None

Problem Summary:

The streaming job metrics regression test queried the configured FE HTTP endpoint, which can be a follower in a multi-FE environment. The doris_fe_job RUNNING gauge and per-job streaming job metrics are produced only on the master FE, so the test could time out even while the streaming job was running.

Resolve the current master FE HTTP address with the regression framework helpers before polling and query metrics from that endpoint.

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test
    • Command: ./run-regression-test.sh --run -dryRun -f regression-test/suites/job_p0/streaming_job/cdc/test_streaming_mysql_job_metrics.groovy
    • Result: the dry-run loaded the selected suite successfully, with 1 suite and 0 failures. Full CDC execution was not run locally.
  • No need to test or manual test.

• 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?

[JNSimba]

run buildall

[JNSimba]

/review

[github-actions]

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[JNSimba]

run buildall

[JNSimba]

run buildall

[JNSimba]

/review

[github-actions]

Codex automated review failed and did not complete.

Error: All Codex review accounts are usage-limited; earliest retry is 2026-08-08T03:32:00Z.
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[liaoxin01]

LGTM