[PSM interop] Don't fail url_map target if sub-target already failed (#33520)

Follow up change of #33222.

We don't want file multiple bugs if any of the sub-tests of the
`url_map` test fails.

tools/internal_ci/linux/grpc_xds_url_map.sh

@@ -143,7 +143,7 @@ main() {
   build_docker_images_if_needed
   # Run tests
   cd "${TEST_DRIVER_FULL_DIR}"
-  run_test url_map
+  run_test url_map || echo "Failed url_map test"
 }
 
 main "$@"

tools/internal_ci/linux/grpc_xds_url_map_python.sh

@@ -153,7 +153,7 @@ main() {
   build_docker_images_if_needed
   # Run tests
   cd "${TEST_DRIVER_FULL_DIR}"
-  run_test url_map
+  run_test url_map || echo "Failed url_map test"
 }
 
 main "$@"