PHP: The www53 FPM pool should use socket instead of port to fix possible legacy issues.

Note that we are breaking backward compatibility here, so it will cause downtime on upgrade from any too old BOA version, until you will upgrade also Octopus instance(s). But we need to move away from using legacy configuration. Make sure you don't use TCP/port mode for PHP-FPM in any custom, non-standard config include, or change it to socket (current default).
Merge branch 'refs/heads/2.3.x-dev'