Extract Project ID from name during AlertPolicy import (#15800)

Co-authored-by: James Edouard <[email protected]>

Author: jedouard1994

mmv1/products/monitoring/AlertPolicy.yaml

@@ -37,7 +37,7 @@ timeouts:
   delete_minutes: 20
 custom_code:
   constants: 'templates/terraform/constants/monitoring_alert_policy.go.tmpl'
-  custom_import: 'templates/terraform/custom_import/self_link_as_name.tmpl'
+  custom_import: 'templates/terraform/custom_import/self_link_as_name_set_project.go.tmpl'
 error_retry_predicates:
 
   - 'transport_tpg.IsMonitoringConcurrentEditError'