ALLJOYN-2425 Removed check for uniquename from removesessionmember test

Since the session contains multiple members any of those members could have
triggered the session_member_added_flag.  Also a second member could be changing
the member_added_unique name while we are checking since multiple threads are
running at the same time.  This check was a verification check, and is unimportant
to the final result of the test so it has been removed to prevent false errors.

Change-Id: I765402b374aeecfe2ca843e3d43a039942efa074