This was copy pasted from the gerrit config and we didn't
s/gerrit/etherpad/ on the log file path for port 80 vhost.
Change-Id: Ie5494c239360a6de3042f34cc3dc050867b92b39
Upstream likes building the settings file into the image, but that's
less exciting, let's bind-mount ours in.
Depends-On: https://review.opendev.org/717491/
Change-Id: Ia1894d884ef2a84e1282345b77fe07bf8898f367