Drop `merge_requests_require_code_owner_approval` column from projects table
As a cleanup task following #13251 (closed) and the deployment of !16187 (merged), we can drop the merge_requests_require_code_owner_approval
column from the projects
table. code_owner_approval_required
(COAR) checks will be done against the protected branches themselves, leaving us without any use for the project level flag.
Edited by Kerri Miller