[configs/releng] pacman 4.1 compatibility

* Remove the unattended-keyring-init patch as this was applied by upstream with pacamn 4.1
* Update our pacman.conf following the new upstream default

Signed-off-by: Pierre Schmitz <pierre@archlinux.de>
Signed-off-by: Gerardo Exequiel Pozzi <vmlinuz386@yahoo.com.ar>
[archiso] Prepare release

Signed-off-by: Gerardo Exequiel Pozzi <vmlinuz386@yahoo.com.ar>