Revert "Update gapic/templates/%namespace/%name_%version/%sub/services/%service/client.py.j2"

This reverts commit 0f68169.

Author: parthea

gapic/templates/%namespace/%name_%version/%sub/services/%service/client.py.j2

@@ -31,9 +31,7 @@ from google.auth.transport import mtls                            # type: ignore
 from google.auth.transport.grpc import SslCredentials             # type: ignore
 from google.auth.exceptions import MutualTLSChannelError          # type: ignore
 from google.oauth2 import service_account                         # type: ignore
-
 {{ shared_macros.add_google_api_core_version_header_import(service) }}
-
 try:
     OptionalRetry = Union[retries.Retry, gapic_v1.method._MethodDefault, None]
 except AttributeError:  # pragma: NO COVER