Switch default php to 8.0 and move php7 to testing

ATM PHP 8.1.0 is out and very probably 3.16 should package both php7 and php8 as few aports still require 7.4

List of incompatible with php8 is not big - tsc#40 (closed)

• build list of packages incompatible with php8, make sure no issues like !27815 (merged) happens
  • community/rutorrent - !29837 (closed) https://github.com/Novik/ruTorrent/issues/2226
  • community/zoneminder - !29838 (merged)
  • community/homer-api - #13459 (closed)
  • community/xapian-bindings - #13461 (closed)
  • community/zabbix - #13460 (closed)
  • testing/kopano-* #13471 (closed) and testing/z-push
• fix package configs (php7-fpm and logrotate configs)
• consider to provide php-fpm configs per each web-app requiring it (nginx,apache,other web frontend) to simplify upgrade to 8.1 for 3.17 #12966 (closed)
• flip default version for edge !28004 (merged)