roles/php-fpm: Fix logic

First, we cannot do a global check for has_wordpress or needs_php,
as those are defined per nginx vhost. Second, I realized that this
was only working in the past because vhosts that had WordPress or
needed PHP were listed first in the nginx_vhosts dict.

This changes the logic to first check if any vhosts have WordPress
or need PHP, then sets a fact that we can use to decide whether to
run php-fpm tasks or not.

roles/php-fpm/tasks/Ubuntu_20.04.yml

@@ -28,7 +28,8 @@
   - name: Update php.ini
     template: src=php7.4-php.ini.j2 dest=/etc/php/7.4/fpm/php.ini owner=root group=root mode=0644
     notify: reload php7.4-fpm
+
   tags: php-fpm
-  when: (item.has_wordpress is defined and item.has_wordpress) or (item.needs_php is defined and item.needs_php)
+  when: install_php
 
 # vim: set ts=2 sw=2: