Add BDD scenarios to git_worktree_coverage_boost.feature and corresponding
step definitions to cover the new error-path cleanup branches introduced by
the TOCTOU race condition fix:
- create() cleanup of _parent_temp_dir on TimeoutExpired during worktree add
- create() cleanup of _parent_temp_dir on CalledProcessError during worktree add
- commit() cleanup of _parent_temp_dir on TimeoutExpired
- rollback() cleanup of _parent_temp_dir on TimeoutExpired
- cleanup() OSError handler when removing parent temp directory
These branches were previously uncovered, causing the CI coverage job to
fail below the 97% threshold.
ISSUES CLOSED: #7507
HAL9000
Jeffrey Phillips Freeman