mon/AuthMonitor: shutdown session connection on auth failure

mon/AuthMonitor: shutdown session connection on auth failure

Currently the mons will allow the session to persist even though an auth
failure has occurred, probably while trying to obtain new tickets.

A sequence to easily trigger this:

    ceph auth rotate osd.0
    ceph auth wipe-rotating-service-keys

The osd.0 will continue interacting with the mons until restart or a network
interruption occurs.

Signed-off-by: Patrick Donnelly <pdonnell@ibm.com>