This comes up a lot when triggering wpt-2013 and wpt-2020. Instead of
merging the jobs and triggering both layouts, the try parser will
trigger two separate jobs. Running two of the same builds at once seems
to cause the CI to fail one of them [1]. This fixes that issue.

1. An example of this: https://github.com/servo/servo/actions/runs/7892269495

Co-authored-by: Samson <16504129+sagudev@users.noreply.github.com>

Co-authored-by: Samson <16504129+sagudev@users.noreply.github.com>