[fix](regression) fix regression test_hive_ctas_to_doris failure

[jacktengg]

What problem does this PR solve?

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.
Don't know what should be done next? See How to process your PR.

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?

[jacktengg]

run buildall

[jacktengg]

/review

[github-actions]

Reviewed PR #64553. I found no blocking issues in the actual PR diff.

Code-review checkpoint conclusions:

• Goal and proof: The PR makes test_hive_ctas_to_doris explicitly enable enable_strict_cast before the CTAS cases that already expect strict-mode filtered-data failures. This matches the suite intent, and the unchanged expected output still covers the successful CTAS paths.
• Scope: The change is small and focused: one session variable set in one external regression suite.
• Concurrency and lifecycle: No new concurrency is introduced. The setting is a session variable on the suite JDBC connection, not a global variable, so normal per-suite execution does not leak it to unrelated suites.
• Configuration: No new config item is added; this uses an existing session variable.
• Compatibility, persistence, transactions, and storage formats: Not applicable; this is test-only and does not change product code or persisted formats.
• Parallel paths: Related strict-mode external tests already set enable_strict_cast explicitly around strict-mode expectations; this CTAS suite now does the same.
• Special conditions: No new conditional logic is added.
• Test coverage and result files: No .out update is needed because the successful query outputs are unchanged. GitHub status shows External Regression succeeded; I did not rerun the external regression locally in this runner.
• Observability, performance, and security: Not applicable for this test-only change.
• User focus: No additional user-provided review focus was present.

Residual note: the existing suite still uses legacy try/catch assertions for expected errors instead of the newer test { sql ...; exception ... } style, but this PR does not introduce that pattern.

[HappenLee]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.