Merge pull request #7093 from murgatroid99/run_interop_override_server_fix

Fix bug with override_server flag in run_interop_tests.py

tools/run_tests/run_interop_tests.py

@@ -470,7 +470,8 @@ def cloud_to_prod_jobspec(language, test_case, server_host_name,
           flake_retries=5 if args.allow_flakes else 0,
           timeout_retries=2 if args.allow_flakes else 0,
           kill_handler=_job_kill_handler)
-  test_job.container_name = container_name
+  if docker_image:
+    test_job.container_name = container_name
   return test_job
 
 
@@ -506,7 +507,8 @@ def cloud_to_cloud_jobspec(language, test_case, server_name, server_host,
           flake_retries=5 if args.allow_flakes else 0,
           timeout_retries=2 if args.allow_flakes else 0,
           kill_handler=_job_kill_handler)
-  test_job.container_name = container_name
+  if docker_image:
+    test_job.container_name = container_name
   return test_job