The helper in question is called in two places:
1. In main() as a fuse against early exception before creating the
drain_on_shutdown() defer
2. In the stop_gossiping() API call
Both can be replaced with the stop_gossiping() call from the .stop()
method, here's why:
1. In main the gossiper::stop() call is already deferred right after
the gossiper is started. So this change moves it above. It may
happen that an exception pops up before the old fuse was deferred,
but that's OK -- the stop_gossiping() is safe against early- and
re- entrances
2. The stop_gossiping() change is effectlvey a rename -- it calls the
stop_gossiping() as it did before, but with the help of the .stop()
method
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>