Check subsequent functionality in CCBC-275 test

Previously it was mistakenly assumed that the reason for not checking
the return code of operations which were to succeed was because of
issues in the Mock. in fact this is because the SASL context has not
actually been reset in lcb_failout_server

Change-Id: I0af4ae7e850c6f41c582d8f297d43ec188412527
Reviewed-on: http://review.couchbase.org/29690
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>