tools: keep PR titles/description up-to-date

Set the `update-pull-request-title-and-body` option when potentially
updating an existing PR with a dynamic title and/or description.

PR-URL: #47621
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: tniessen