Do not touch hostname and timezone

Let's let the admin set them as they wish.
We don't care what they are anyway.

If other things run on the same server,
it's also better not to hijack these for our
own purposes, especially when we don't need to.

The timedatectl call also seems to fail on Ubuntu 17.04
for some reason (missing timezones information file?).

roles/matrix-server/tasks/setup_base.yml

@@ -38,10 +38,3 @@
 
 - name: Ensure SELinux disabled
   selinux: state=disabled
-
-- name: Ensure correct hostname set
-  hostname: name="{{ hostname_matrix }}"
-
-- name: Ensure timezone is UTC
-  timezone:
-    name: UTC