community/nextcloud: miscellaneous improvements
fpm-pool.conf: Need to specify user and group else php-fpm8 cannot start
nextcloud-initscript.post-install: Using install in APKBUILD caused /var/tmp to become 755, so create with mkdir in the post install. Also because of the switch to php8, the settings are in /etc/php8/fpm.d/nextcloud.conf
nextcloud-mysql.cnf: MariaDB 10.6 has started deprecating write support for compressed tables, but Nextcloud requires write support. See https://github.com/nextcloud/server/issues/25436