[AIRFLOW-4856] change hard coded run_as_user

change the default value to it's old 65533

airflow/config_templates/default_airflow.cfg

@@ -675,7 +675,7 @@ git_ssh_known_hosts_configmap_name =
 git_sync_container_repository = k8s.gcr.io/git-sync
 git_sync_container_tag = v3.1.1
 git_sync_init_container_name = git-sync-clone
-git_sync_run_as_user =
+git_sync_run_as_user = 65533
 
 # The name of the Kubernetes service account to be associated with airflow workers, if any.
 # Service accounts are required for workers that require access to secrets or cluster resources.