Replace dump_json_test_results flag by isolated-script-test-output.

This is because it's the default flag used in the recipes to dump a json output.
This CL also fixes some python3 lint issues in mb.py.

Bug: webrtc:13594
Change-Id: I9275b5da0963f801d3191703c2eb72d90befb5d7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/248142
Reviewed-by: Christoffer Jansson <jansson@google.com>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Jeremy Leconte <jleconte@google.com>
Cr-Commit-Position: refs/heads/main@{#35986}
diff --git a/tools_webrtc/gtest-parallel-wrapper.py b/tools_webrtc/gtest-parallel-wrapper.py
index 3b07da4..2972e6c 100755
--- a/tools_webrtc/gtest-parallel-wrapper.py
+++ b/tools_webrtc/gtest-parallel-wrapper.py
@@ -135,9 +135,11 @@
   # These options will be passed unchanged to gtest-parallel.
   gtest_group.AddArgument('-d', '--output_dir')
   gtest_group.AddArgument('-r', '--repeat')
-  # TODO(webrtc:13556): use isolated-script-test-output argument instead
-  # of dump_json_test_results as it was done prior to chromium:1051927.
-  gtest_group.AddArgument('--dump_json_test_results')
+  # --isolated-script-test-output is used to upload results to the flakiness
+  # dashboard. This translation is made because gtest-parallel expects the flag
+  # to be called --dump_json_test_results instead.
+  gtest_group.AddArgument('--isolated-script-test-output',
+                          dest='dump_json_test_results')
   gtest_group.AddArgument('--retry_failed')
   gtest_group.AddArgument('--gtest_color')
   gtest_group.AddArgument('--gtest_filter')