[core] Optimize data evolution conflict scans

[leaves12138]

Purpose

Unify Data Evolution base-file conflict scanning around the available selectors instead of maintaining separate compact and overwrite paths.

• Scan current data files by changed row ranges when row IDs are available.
• Supplement or select files by filename for deletion-vector and deleted-file references.
• Skip base-file scans when no row-range or filename selector exists.
• Pass the duplicate-discard requirement into conflict detection and retain changed-partition scans when all APPEND files must be checked for duplicate identifiers.

Tests

• mvn -pl paimon-core -DwildcardSuites=none -Dtest=ConflictDetectionTest test
• mvn -pl paimon-core -Pfast-build -DwildcardSuites=none -Dtest=AppendOnlySimpleTableTest#testDiscardDuplicateFiles test
• mvn -pl paimon-core -Pfast-build -DwildcardSuites=none -Dtest=DataEvolutionDeletionVectorTest test

[JingsongLi]

[P1] Preserve explicit APPEND conflict scans

This empty fallback also applies when recovery explicitly requests checkAppendFiles=true. Ordinary Data Evolution APPEND files still have firstRowId == null at this point because row tracking is assigned later, so they provide neither a row-range selector nor a referenced filename. Replaying an already committed committable is therefore accepted instead of being compared with the live base file. In an end-to-end reproduction, the recovery commit advanced the snapshot and the same physical row was returned twice; the base branch rejects the replay with Trying to add file ... already in the map.

Please propagate the explicit append-file conflict-check requirement separately from discardDuplicate and retain the changed-partition scan for non-empty APPEND deltas when that check is requested. Index-only APPENDs can keep the selective path.

[JingsongLi]

+1