Revert "Revert "Merge branch '18193-developers-can-merge' into 'master'""
## What does this MR do?
Reverts the revert of !4892 which lacked an EE MR at the time. This has been done in gitlab-org/gitlab-ee!564.
## What are the relevant issue numbers?
Closes #19872.
See merge request !5310
