Deploy new `purged` version with the UDS feature (https://gerrit.wikimedia.org/r/c/operations/software/purged/+/957362).
Roughly the list of activities should be:
- [x] Build the package for bullseye and import in APT repository
- [x] Upgrade on single cp host for test (cp4040)
- [x] Set `profile::cache::purge::frontend_addr: "/run/varnish-privileged.socket"` on test host (cp4040) and apply puppet
- [x] restart `purged` service on test host (cp4040) monitor that PURGE requests will be handled correctly by the new varnish configuration (T347192)
- [x] Upgrade `purged` package on all bullseye cp hosts: `sudo cumin 'A:cp and A:bullseye' 'apt-get install -y purged=0.21+deb11u1'`
- [x] Rebuild the package (with different versioning) for bookworm
- [x] Upgrade `purged` package on all bookworm cp hosts: `sudo cumin 'A:cp and A:bookworm' 'apt-get install -y purged=0.21+deb12u1'` (only cp4052)
- [x] Modify the `purged` systemd unit to switch to UDS socket (puppet)
- [] Apply `profile::cache::purge::frontend_addr: "/run/varnish-privileged.socket"` to all cache hosts. `purged` service is restarted as puppet applies the systemd unit changes.
- [x] ulsfo
- [x] codfw
- [x] eqsin
- [x] eqiad
- [x] drmrs
- [] esams
- [x] Update eventual documentation about this