Reland "Speculatively serialize trace_test on Win NVIDIA GTX 1660"

This reverts commit bd3e808d49bbe5ae92dc9a1073c2f4712ae43501.

Reason for revert:
hangs were happening where serialization didn't apply
with the serialization removed there are more hangs than before

Also make sure serialization applies to win_optional_gpu_tests_rel.

Bug: 406454932
Original change's description:
> Revert "Speculatively serialize trace_test on Win NVIDIA GTX 1660"
>
> This reverts commit d37b39a8e8f10b4eb2c0a4bc20ca4848c150b913.
>
> Reason for revert: hangs still happen
>
> Bug: 406454932
> Original change's description:
> > Speculatively serialize trace_test on Win NVIDIA GTX 1660
> >
> > Parallelization suspect for flaky machine hangs on this platform.
> >
> > Bug: 406454932
> > Change-Id: I36582f2fed1ec958fff179d0b39b50c63831387f
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6397476
> > Auto-Submit: Yuly Novikov <ynovikov@chromium.org>
> > Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
> > Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
> > Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#1438367}
>
> Bug: 406454932
> Change-Id: Iac3c66aa399305de2eedd6a16614957b43130b94
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6532906
> Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
> Auto-Submit: Yuly Novikov <ynovikov@chromium.org>
> Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
> Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1458298}

Bug: 406454932
Change-Id: Ibb9074c7e25795f8d20da00272026407e866af9c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6546817
Auto-Submit: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1460204}
NOKEYCHECK=True
GitOrigin-RevId: 51f80bcaf469b37aabf909a9ca1ac1a5e82ef515
diff --git a/buildbot/buildbot_json_magic_substitutions.py b/buildbot/buildbot_json_magic_substitutions.py
index 37f93be..b608f9f 100644
--- a/buildbot/buildbot_json_magic_substitutions.py
+++ b/buildbot/buildbot_json_magic_substitutions.py
@@ -357,6 +357,15 @@
       if gpu.startswith('10de'):
         return ['--jobs=1']
 
+  # trace_test flakily hangs Win NVIDIA GTX 1660 machines crbug.com/406454932.
+  # Speculatively disable parallelism to check if it is related.
+  is_trace_test = (test_name.startswith('trace_test')
+                   or test_config.get('telemetry_test_name') == 'trace_test')
+  if os_type == 'win' and is_trace_test:
+    for gpu in _GetGpusFromTestConfig(test_config):
+      if gpu.startswith('10de:2184'):
+        return ['--jobs=1']
+
   if os_type in ['lacros', 'linux', 'mac', 'win']:
     return ['--jobs=4']
   return ['--jobs=1']
diff --git a/buildbot/client.v8.fyi.json b/buildbot/client.v8.fyi.json
index 185fae1..9429790 100644
--- a/buildbot/client.v8.fyi.json
+++ b/buildbot/client.v8.fyi.json
@@ -3028,7 +3028,7 @@
           "--stable-jobs",
           "--extra-browser-args=--enable-logging=stderr --js-flags=--expose-gc",
           "--enforce-browser-version",
-          "--jobs=4"
+          "--jobs=1"
         ],
         "merge": {
           "script": "//testing/merge_scripts/standard_isolated_script_merge.py"