Fix hash PK rollback after failed COPY

[adsharma]

Summary

Fix failed COPY rollback for hash primary-key indexes by making discardPrimaryKey() discard only uncommitted local insertions instead of recording a local deletion.

Root Cause

The regression was introduced by b2055a915 (Add ART primary key index). That commit added a generic discardPrimaryKey() rollback hook and wired the hash primary-key index implementation to delete_().

For hash indexes, delete_() can create local deletion markers. During the failed duplicate-PK COPY rollback, those markers could mask rows from the subsequent successful COPY. This showed up in the WASM in-memory kernel test as transaction~copy~copy_node.CopyNodeAfterPKErrorRollbackFlushedGroups returning no row for Comment.ID = 962073046352.

The first scheduled main failure after the May 16 successful run was May 17 at 7d6335a7b, with the same failing test; the relevant regression range starts at b2055a915.

Change

PrimaryKeyIndex::discardPrimaryKey() now removes matching keys only from local uncommitted hash-index insertions via discardLocal(). It no longer calls delete_() and therefore does not add local deletion entries during COPY rollback.

Validation

• make test-build-release
• IN_MEM_MODE=true E2E_TEST_FILES_DIRECTORY=test/test_files build/release/test/runner/e2e_test --gtest_filter='transaction~copy~copy_node.CopyNodeAfterPKErrorRollbackFlushedGroups'
• E2E_TEST_FILES_DIRECTORY=test/test_files build/release/test/runner/e2e_test --gtest_filter='transaction~copy~copy_node.CopyNodeAfterPKErrorRollbackFlushedGroups'

[adsharma]

https://github.com/LadybugDB/ladybug/actions/runs/26473310530