roles/php-fpm: Use set_fact to set packages

Instead of looping over a list of items to install, we can actually
just give a list directly to the apt module. This allows the module
to install all packages in one transaction, which is faster as well
as slightly safer for some dependency resolution scenarios.

roles/php-fpm/tasks/Ubuntu.yml

@@ -1,17 +1,20 @@
 ---
 
 - block:
+  - name: Set php-fpm packages
+    set_fact:
+      php_fpm_packages:
+        - php7.0-fpm
+        # for WordPress
+        - php7.0-mysql
+        - php7.0-gd
+        - php7.0-curl
+        # for Piwik
+        - php7.0-mbstring
+        - php7.0-xml
+
   - name: Install php7.0-fpm and deps
-    apt: name={{ item }} state=present update_cache=yes
-    loop:
-      - php7.0-fpm
-      # for WordPress
-      - php7.0-mysql
-      - php7.0-gd
-      - php7.0-curl
-      # for Piwik
-      - php7.0-mbstring
-      - php7.0-xml
+    apt: name={{ php_fpm_packages }} state=present update_cache=yes
 
   # only copy php-fpm config for vhosts that need WordPress or PHP
   - name: Copy php-fpm pool config

roles/php-fpm/tasks/Ubuntu_18.04.yml

@@ -1,17 +1,20 @@
 ---
 
 - block:
+  - name: Set php-fpm packages
+    set_fact:
+      php_fpm_packages:
+        - php-fpm
+        # for WordPress
+        - php-mysql
+        - php-gd
+        - php-curl
+        # for Piwik
+        - php-mbstring
+        - php-xml
+
   - name: Install php-fpm and deps
-    apt: name={{ item }} state=present update_cache=yes
-    loop:
-      - php-fpm
-      # for WordPress
-      - php-mysql
-      - php-gd
-      - php-curl
-      # for Piwik
-      - php-mbstring
-      - php-xml
+    apt: name={{ php_fpm_packages }} state=present update_cache=yes
 
   # only copy php-fpm config for vhosts that need WordPress or PHP
   - name: Copy php-fpm pool config