filter Insights credentials from /api/v1/credentials/

see: #6978
see: #6088

awx/api/filters.py

@@ -39,9 +39,11 @@ class V1CredentialFilterBackend(BaseFilterBackend):
     '''
 
     def filter_queryset(self, request, queryset, view):
+        # TODO: remove in 3.3
         from awx.api.versioning import get_request_version
         if get_request_version(request) == 1:
             queryset = queryset.filter(credential_type__managed_by_tower=True)
+            queryset = queryset.filter(~Q(credential_type__kind='insights'))
         return queryset