[test](search) Add regression test for wildcard query on variant subcolumns with multi-index

[airborne12]

What problem does this PR solve?

Related PR: #60793

Problem Summary:
Wildcard queries (*, ?) on variant subcolumns with multiple inverted indexes (one without analyzer, one with standard/lowercase analyzer) previously returned empty results even when regular TERM search worked correctly.

This PR adds a regression test (test_search_variant_wildcard_custom_analyzer) to verify the fix from #60793 with a more realistic scenario matching the HubSpot contacts table pattern:

• Variant column with dual field_pattern indexes (none + standard/lowercase)
• firstname/lastname stored in variant subcolumns (string_8, string_17)
• 13 test cases covering: TERM baseline, leading/middle/trailing/single-char wildcards, cross-field AND, and match-all wildcard

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

[Thearas]

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?

[airborne12]

run buildall