gce_instance_template: fix allow the setting of the service account (#29154)

lib/ansible/modules/cloud/google/gce_instance_template.py

@@ -290,6 +290,7 @@ def create_instance_template(module, gce):
     external_ip = module.params.get('external_ip')
     service_account_permissions = module.params.get(
         'service_account_permissions')
+    service_account_email = module.params.get('service_account_email')
     on_host_maintenance = module.params.get('on_host_maintenance')
     automatic_restart = module.params.get('automatic_restart')
     preemptible = module.params.get('preemptible')
@@ -369,7 +370,10 @@ def create_instance_template(module, gce):
                 bad_perms.append(perm)
         if len(bad_perms) > 0:
             module.fail_json(msg='bad permissions: %s' % str(bad_perms))
-        ex_sa_perms.append({'email': "default"})
+        if service_account_email is not None:
+            ex_sa_perms.append({'email': str(service_account_email)})
+        else:
+            ex_sa_perms.append({'email': "default"})
         ex_sa_perms[0]['scopes'] = service_account_permissions
     gce_args['service_accounts'] = ex_sa_perms