fix: keep every spilled slice of a sort-merge join inner key group

[buraksenn]

Which issue does this PR close?

• No issue. Found while adding test coverage in scope of Improve test coverage for spilling (memory-limited) sort/aggregation/sort-merge-join #13431.

Rationale for this change

Filtered semi, anti, and mark sort-merge joins kept only one finished spill file per inner key group. If a group spilled more than once, each spill replaced the previous file, so read-back could lose earlier rows and produce incorrect results.

What changes are included in this PR?

Keep one InProgressSpillFile open per inner key group, append every overflow to it, and finalize it before filter evaluation.

Are these changes tested?

Yes:

cargo test -p datafusion-physical-plan bitwise_multi_spill_inner_key_group
cargo test -p datafusion-physical-plan
cargo test --test sqllogictests -- sort_merge_join_spill

Are there any user-facing changes?

no

[codecov-commenter]

Codecov Report

❌ Patch coverage is 85.71429% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.86%. Comparing base (66c3840) to head (626f325).

Files with missing lines	Patch %	Lines
...l-plan/src/joins/sort_merge_join/bitwise_stream.rs	85.71%	0 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #24056      +/-   ##
==========================================
- Coverage   80.86%   80.86%   -0.01%     
==========================================
  Files        1101     1101              
  Lines      375446   375455       +9     
  Branches   375446   375455       +9     
==========================================
+ Hits       303592   303594       +2     
- Misses      53761    53765       +4     
- Partials    18093    18096       +3     

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[kumarUjjawal]

Thank you @buraksenn

Looks good!