fix: use correct user when checking the DB (#3000)

kubernetes/ansible/roles/kong-migration/tasks/main.yml

@@ -2,7 +2,7 @@
   docker_container:
     name: postgres
     image: postgres
-    command: 'psql -h {{ kong_postgres_host }} -U postgres -d {{ kong_postgres_database }} -p 5432 -c "\dt"'
+    command: 'psql -h {{ kong_postgres_host }} -U {{ kong_postgres_user }} -d {{ kong_postgres_database }} -p 5432 -c "\dt"'
     detach: false
     cleanup: yes
     env: