Remove non-applicable test (database purges)

This test was previously already disabled, but now gets removed
completely.

With UPR the view engine doesn't need to deal with database purges
anymore. Purged data in a database will just show up as a deleted
item in the UPR stream.

Change-Id: Iec04798c70d077536f568355f958da96f0a3c47c
Reviewed-on: http://review.couchbase.org/33123
Tested-by: Volker Mische <volker.mische@gmail.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>