Remove obsolete distinct filtered join wrapper

[PointKernel]

Description

This PR removes the obsolete cudf::detail::distinct_filtered_join wrapper and moves its semi/anti join implementation into cudf::detail::filtered_join.

Since cudf::mark_join handles left-table reuse and cudf::filtered_join handles right-table reuse, filtered join has only one concrete implementation. This removes the unnecessary virtual hierarchy and keeps hash-table construction, insertion, and probing in one class without changing behavior.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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[PointKernel]

/ok to test 810dddb

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📥 Commits

Reviewing files that changed from the base of the PR and between 5ba02d1 and 810dddb.

📒 Files selected for processing (7)

• cpp/include/cudf/detail/join/distinct_filtered_join.cuh
• cpp/include/cudf/detail/join/filtered_join.cuh
• cpp/src/join/filtered_join/filtered_join.cu
• cpp/src/join/filtered_join/filtered_join_common.cuh
• cpp/src/join/filtered_join/filtered_join_flat.cu
• cpp/src/join/filtered_join/filtered_join_nested_query.cu
• cpp/src/join/filtered_join/filtered_join_primitive.cu

💤 Files with no reviewable changes (1)

• cpp/include/cudf/detail/join/distinct_filtered_join.cuh

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📝 Walkthrough

Summary by CodeRabbit

• Improvements
  • Streamlined filtered join processing by consolidating semi-join and anti-join execution.
  • Maintained support for primitive, flat, and nested table queries.
  • Improved handling of query-result storage for filtered joins.
  • Updated join operation reporting for clearer diagnostics.

Walkthrough

The PR removes distinct_filtered_join and consolidates its semi/anti join execution and probing helpers into filtered_join. The public wrapper now constructs filtered_join, which supports primitive, flat, and nested probing through shared helpers.

Changes

Filtered join consolidation

Layer / File(s)	Summary
Filtered join contract and probing helpers cpp/include/cudf/detail/join/filtered_join.cuh	filtered_join becomes concrete and declares shared semi/anti execution and probing helpers. Query match state uses cudf::device_span<bool>.
Filtered join execution and method ownership cpp/src/join/filtered_join/*	Constructor, semi/anti methods, right-table queries, and wrapper construction move from distinct_filtered_join to filtered_join.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related issues

• [FEA] Rewrite mixed join internals using normal join + pre/post-filtering #22124 — Refactors the same filtered-join semi/anti execution area.

Possibly related PRs

• rapidsai/cudf#23012 — Refactors filtered and mixed join execution around shared filtered-join functionality.
• rapidsai/cudf#23320 — Introduces filtered-join probing helpers that this PR moves into filtered_join.
• rapidsai/cudf#23395 — Rewrites mixed joins using filtered joins and shared semi/anti infrastructure.

Suggested reviewers: vyasr, kingcrimsontianyu, ttnghia

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the removal of the obsolete wrapper, which is the primary change in the pull request.
Description check	✅ Passed	The description accurately explains the wrapper removal, implementation consolidation, and behavior preservation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[PointKernel]

/merge