We can now specify the trials for clusterfuzz using the file
clusterfuzz_trials_config.json. There is also a presubmit check
to make sure that it is formatted correctly.

Change-Id: Iafb7063b63b1daeb7653830542d13b419cf187d6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3416191Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Almothana Athamneh <almuthanna@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78848}