Enable stale action (#28729)

Follows #28695

Now that the action has run successfully in debug mode
([logs](https://github.com/facebook/react/actions/runs/8532177618/job/23372921455#step:2:35)),
let's enable it to persist changes.

Also changes the number of operations per run from the default of 30 to
100 since we have a large backlog of issues and PRs to work through.

Finally adds enhancement label as exempt from stale.