Refresh buster-php81-* images to upgrade php
The current images provide php 8.1.13 while sury now provides 8.1.18. Since sury does seem to provide archives of old packages, I was unable to retrieve the debugging symbol package for the old PHP version.
In the future we would probably need a child image that includes debugging symbols.
Rebuild:
buster-php81 buster-php81-fpm buster-php81-jobrunner
Bug: T338208