Merge branch '458159-move-multiple-deployments-limit-from-top-level-namespace-to-project-if-unique_domain-is' into 'master' 

Move Multiple Deployments limit from top-level namespace to project if  `unique_domain` is enabled.

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/173818



Merged-by: Janis Altherr <jaltherr@gitlab.com>
Approved-by: Buck O'Leary <bucoleary@gitlab.com>
Approved-by: Savas Vedova <svedova@gitlab.com>
Reviewed-by: Savas Vedova <svedova@gitlab.com>
Reviewed-by: Janis Altherr <jaltherr@gitlab.com>