chore: remove obsolete var

resources/hydra/kustomization.yaml

@@ -31,10 +31,3 @@ vars:
     apiVersion: batch/v1
   fieldref:
     fieldpath: metadata.name
-- name: HYDRA_POSTGRES_SERVICE_NAME
-  objref:
-    name: hydra-migrate
-    kind: Job 
-    apiVersion: batch/v1
-  fieldref:
-    fieldpath: metadata.name