fix(zabbixserver): Fix env vars

If we want to override RESTART_POLICY we have to
spell it with an underscore and not as
RESTARTPOLICY.

Also TIMEZONE doesn't really exist anymore, it's
PHP_TZ and that is already covered by vars from
Vault so no need to list it separately.

templates.d/zabbixserver/fqdn_context.env

@@ -9,5 +9,4 @@
 # ZBX_DEBUGLEVEL=4
 
 # Other available defaults
-# RESTARTPOLICY=unless-stopped
+# RESTART_POLICY=unless-stopped
-# TIMEZONE=Etc/UTC