Merge branch '478539-policies-parsed-yaml-check' into 'master'

Add extra check for parsed yaml in policy drawer

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/166465



Merged-by: Alexander Turinske <aturinske@gitlab.com>
Approved-by: Alexander Turinske <aturinske@gitlab.com>
Co-authored-by: Artur Fedorov <afedorov@gitlab.com>