fix(hostname): ensure hostname is the FQDN

Previously, the value was compared against `ansible_hostname`,
which only is the FQDN after the first reboot. This lead to the
monitoring not seeing the FQDN as the instance name.

This commit scrapes the hostname using the hostname command,
which is garantueed to return the current running hostname, and
then determines if it needs to be set at runtime.

roles/hostname/tasks/main.yml

@@ -21,8 +21,17 @@
       {% endfor %}
     marker: "# {mark} ANSIBLE MANAGED BLOCK"
 
+# Needed because ansibles `ansible_fqdn` is loaded
+# from /etc/hostname, not from the running hostname
+- name: Query current hostname
+  command:
+    cmd: "hostname"
+  changed_when: false
+  register: current_hostname
+
 - name: Set hostname via hostnamectl to avoid a reboot
   command:
     cmd: "hostnamectl set-hostname {{ hostname_fqdn }}"
-  when: hostname_fqdn != "{{ ansible_fqdn }}."
-
+  when: hostname_fqdn != hostname_current
+  vars:
+    hostname_current: "{{ current_hostname.stdout }}."