channel-request test: avoid a race condition
channel-request test: avoid a race condition

If we emit Succeeded or Failed quickly enough after setting up the
TpProxy, the match rules might not have reached the dbus-daemon yet.

(The real ChannelRequest implementation avoids this bug by having the
Proceed method.)

Reviewed-by: Jonny Lamb <3d1fb3642aaab2ff70e3392a5ab916bf99eed6a3@collabora.co.uk>

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib