fix: remove unnecessary call to mds service

Author: harkamaljot

google/auth/compute_engine/credentials.py

@@ -87,25 +87,6 @@ def __init__(
             self._universe_domain = universe_domain
             self._universe_domain_cached = True
 
-    def _retrieve_info(self, request):
-        """Retrieve information about the service account.
-
-        Updates the scopes and retrieves the full service account email.
-
-        Args:
-            request (google.auth.transport.Request): The object used to make
-                HTTP requests.
-        """
-        info = _metadata.get_service_account_info(
-            request, service_account=self._service_account_email
-        )
-
-        self._service_account_email = info["email"]
-
-        # Don't override scopes requested by the user.
-        if self._scopes is None:
-            self._scopes = info["scopes"]
-
     def _metric_header_for_usage(self):
         return metrics.CRED_TYPE_SA_MDS
 
@@ -123,7 +104,6 @@ def refresh(self, request):
         """
         scopes = self._scopes if self._scopes is not None else self._default_scopes
         try:
-            self._retrieve_info(request)
             self.token, self.expiry = _metadata.get_service_account_token(
                 request, service_account=self._service_account_email, scopes=scopes
             )