Remove ON_SWITCH_CONN events (not used)

Change-Id: Ic3542f6199488f6582f3e3c32cc57a48ba2275ac
Reviewed-on: http://review.couchbase.org/42596
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Dave Rigby <daver@couchbase.com>