Merge pull request #7093 from murgatroid99/run_interop_override_server_fix

Fix bug with override_server flag in run_interop_tests.py
diff --git a/tools/run_tests/run_interop_tests.py b/tools/run_tests/run_interop_tests.py
index d76dd4b..adf9ada 100755
--- a/tools/run_tests/run_interop_tests.py
+++ b/tools/run_tests/run_interop_tests.py
@@ -470,7 +470,8 @@
           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 @@
           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