Merge branch 'jej/remove-dependent-destroy-from-protected-refs' into 'master'

Remove 'dependent: :destroy' from ProtectedRef has_many :"#{type}_access_levels"

See merge request !13835

app/models/concerns/protected_ref.rb

@@ -23,7 +23,7 @@ module ProtectedRef
         # If we don't `protected_branch` or `protected_tag` would be empty and
         # `project` cannot be delegated to it, which in turn would cause validations
         # to fail.
-        has_many :"#{type}_access_levels", dependent: :destroy, inverse_of: self.model_name.singular # rubocop:disable Cop/ActiveRecordDependent
+        has_many :"#{type}_access_levels", inverse_of: self.model_name.singular # rubocop:disable Cop/ActiveRecordDependent
 
         validates :"#{type}_access_levels", length: { is: 1, message: "are restricted to a single instance per #{self.model_name.human}." }