Background

Design: WRITING-39975. Scope: WRITING-39974. Epic: SPM-4886.

MongoDB never sets blind_remove on a leader, but WiredTiger still supports it there. A leader remove always reads the stable table, so nothing is skipped.

Change

• With blind_remove set on a leader, a missing key returns success instead of WT_NOTFOUND. Other errors are unchanged.
• Add the statistic layered_curs_blind_remove_leader: layered table cursor blind remove operations on a leader. It counts using WiredTiger's own role check during the remove.

Tests

Python tests in the same PR cover:

• A missing key returns 0 on a leader, and results without the option are unchanged.
• Stacked deletes: a second blind remove of the same key at a different timestamp, and remove, insert, remove with reads in between. No update chain ends up with two consecutive tombstones.
• The statistic moves as expected.

Acceptance criteria

• Behaviour matches the design. New tests pass, and fail without the change.

Depends on

The blind_remove option ticket (WT-18922).