reworked php7.3 stack

* replace previous stack php7 variables
* properly set stack php = php7.2 and php73 = php7.3
* rename upstream php72 and php73 to avoid issues when migrating from EEv3
* use unix socket in nginx upstream instead of TCP/IP

wo/cli/templates/upstream.mustache

@@ -4,7 +4,7 @@ server 127.0.0.1:9000;
 }
 upstream debug {
 # Debug Pool
-server 127.0.0.1:9100;
+server 127.0.0.1:9001;
 }
 upstream php72 {
 server unix:/var/run/php/php72-fpm.sock;