Discard 'self' from '_joined_groups' if we got booted out

When running watchers we scan over all the currently existing
groups, during this scan of groups and associated members we
can determine if the the member that the driver represents has
been kicked out of the group and clean out our '_joined_group'
set when this has been detected.

Change-Id: Ib17543f2401804d2d3573d9b8bdeb55cb2c9f606
Merge "Discard 'self' from '_joined_groups' if we got booted out"