[fix] dnsmasq conf: remove 'resolv-file' line.

- there is no file specified for this line.
- dns resolution isn't working on some cases:
- metronome could not works.
- https://forum.yunohost.org/t/xmpp-cant-connect-to-conference-yunohost-org/2142

data/templates/dnsmasq/domain.tpl

@@ -1,4 +1,3 @@
-resolv-file=
 address=/{{ domain }}/{{ ip }}
 txt-record={{ domain }},"v=spf1 mx a -all"
 mx-host={{ domain }},{{ domain }},5