fix cannot find tests

tools/internal_ci/macos/grpc_basictests_objc_examples.cfg

@@ -27,5 +27,5 @@ action {
 
 env_vars {
   key: "RUN_TESTS_FLAGS"
-  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --bq_result_table aggregate_results --extra_args '-r ios-buildtest-.*'"
+  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --bq_result_table aggregate_results --extra_args -r ios-buildtest-.*"
 }

tools/internal_ci/macos/grpc_basictests_objc_ios.cfg

@@ -27,5 +27,5 @@ action {
 
 env_vars {
   key: "RUN_TESTS_FLAGS"
-  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --bq_result_table aggregate_results --extra_args '-r ios-test-.*'"
+  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --bq_result_table aggregate_results --extra_args -r ios-test-.*"
 }

tools/internal_ci/macos/grpc_basictests_objc_mac.cfg

@@ -27,5 +27,5 @@ action {
 
 env_vars {
   key: "RUN_TESTS_FLAGS"
-  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --bq_result_table aggregate_results --extra_args '-r mac-test-.*'"
+  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --bq_result_table aggregate_results --extra_args -r mac-test-.*"
 }

tools/internal_ci/macos/pull_request/grpc_basictests_objc_examples.cfg

@@ -27,5 +27,5 @@ action {
 
 env_vars {
   key: "RUN_TESTS_FLAGS"
-  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --extra_args '-r ios-buildtest-.*'"
+  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --extra_args -r ios-buildtest-.*"
 }

tools/internal_ci/macos/pull_request/grpc_basictests_objc_ios.cfg

@@ -27,5 +27,5 @@ action {
 
 env_vars {
   key: "RUN_TESTS_FLAGS"
-  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --extra_args '-r ios-test-.*'"
+  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --extra_args -r ios-test-.*"
 }

tools/internal_ci/macos/pull_request/grpc_basictests_objc_mac.cfg

@@ -27,5 +27,5 @@ action {
 
 env_vars {
   key: "RUN_TESTS_FLAGS"
-  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --extra_args '-r mac-test-.*'"
+  value: "-f basictests macos objc opt --internal_ci -j 1 --inner_jobs 4 --extra_args -r mac-test-.*"
 }

tools/run_tests/run_tests_matrix.py

@@ -246,7 +246,7 @@ def _create_test_jobs(extra_args=[], inner_jobs=_DEFAULT_INNER_JOBS):
     # supported on mac only.
     test_jobs += _generate_jobs(
         languages=['objc'],
-        configs=['dbg'],
+        configs=['opt'],
         platforms=['macos'],
         labels=['basictests', 'multilang'],
         extra_args=extra_args,
@@ -523,6 +523,7 @@ if __name__ == "__main__":
         '--extra_args',
         default='',
         type=str,
+        nargs=argparse.REMAINDER,
         help='Extra test args passed to each sub-script.')
     args = argp.parse_args()
 
@@ -542,7 +543,7 @@ if __name__ == "__main__":
         extra_args.append('%s' % args.bq_result_table)
         extra_args.append('--measure_cpu_costs')
     if args.extra_args:
-        extra_args.extend(('%s' % args.extra_args).split())
+        extra_args.extend(args.extra_args)
 
     all_jobs = _create_test_jobs(extra_args=extra_args, inner_jobs=args.inner_jobs) + \
                _create_portability_test_jobs(extra_args=extra_args, inner_jobs=args.inner_jobs)