fix: Move incus template files into correct role

Moved from system role where they used to be required into the
(currently disabled) incus installation role.

roles/incus-install/files/incus.servers.tpl

@@ -0,0 +1,5 @@
+{% for host in vars['ansible_play_hosts'] | sort %}
+{% if hostvars[host]['incus_name'] == task_name and "cluster" in hostvars[host]['incus_roles'] %}
+- {{ host }}
+{% endif %}
+{% endfor %}