Set paths for tuner and shortfin workflows consistently.

[ScottTodd]

Now these workflows will only run if files in one of these subproject directories are touched.

This sets triggers consistently for pull_request and push events. In other projects we've set all workflows to run on push events. We could do that here too, just in case these triggers miss something prior to merge.

Note that using paths filters on pull_request triggers breaks "required checks". We currently only set pre-commit and Unit Tests and Type Checking (3.11, ubuntu-latest) as required checks though.

Another option is to just always run these workflows with no filters at all. The workflows are using free runners and are pretty fast (~5 minutes), so the predictability could be nice.