With the current state, someone wanting to overrde the dnsmasq
configuration, could think that defining overrides would work.
However, there is no section headers for dnsmsasq and templating with
config_template never worked. We can use what's already included in
the template, and rely on the template module instead.
Change-Id: Icf6cf1c7b7feee893fd311403a284ae512011a2e
Closes-Bug: #1697981