[PSM Interop] Log Google Cloud API debug header part 2 (#34687)

We're seeing too many debug headers, change it to only log header in
case of error.

<!--

If you know who should review your pull request, please assign it to
that
person, otherwise the pull request would get assigned randomly.

If your pull request is for a specific language, please add the
appropriate
lang label.

-->

tools/run_tests/xds_k8s_test_driver/framework/infrastructure/gcp/compute.py

@@ -585,7 +585,7 @@ class ComputeV1(
 
     @staticmethod
     def _log_debug_header(resp: httplib2.Response):
-        if DEBUG_HEADER_IN_RESPONSE in resp:
+        if DEBUG_HEADER_IN_RESPONSE in resp and resp.status >= 300:
             logger.info(
                 "Received GCP debug headers: %s",
                 resp[DEBUG_HEADER_IN_RESPONSE],