muc/roomlist.py: stop testing pre-Requests API
muc/roomlist.py: stop testing pre-Requests API

We have equivalent test coverage for CreateChannel().

Also stop listening for the NewChannel signal.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=69618
Reviewed-by: Guillaume Desmottes <f16649c7afcd84e3350287183c4ed23cb1aea57c@collabora.co.uk>

Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble