Merge pull request #20074 from jtattermusch/portability_libuv_logs

Only run libuv portability tests as build-only

tools/run_tests/run_tests_matrix.py

@@ -403,13 +403,17 @@ def _create_portability_test_jobs(extra_args=[],
         extra_args=extra_args,
         inner_jobs=inner_jobs)
 
+    # TODO(jtattermusch): a large portion of the libuv tests is failing,
+    # which can end up killing the kokoro job due to gigabytes of error logs
+    # generated. Remove the --build_only flag
+    # once https://github.com/grpc/grpc/issues/17556 is fixed.
     test_jobs += _generate_jobs(
         languages=['c'],
         configs=['dbg'],
         platforms=['linux'],
         iomgr_platforms=['uv'],
         labels=['portability', 'corelang'],
-        extra_args=extra_args,
+        extra_args=extra_args + ['--build_only'],
         inner_jobs=inner_jobs,
         timeout_seconds=_CPP_RUNTESTS_TIMEOUT)