ep_testsuite: Expand Delete-with-value test cases

ep_testsuite: Expand Delete-with-value test cases

Expand the ep_testsuite tests for Deletes with a value. Ensure that
all possible state transitions (between Alive, Deleted-with-value &
Deleted-no-value) are handled.

Note that the Delete-with-value -> Delete-no-value transition cannot
be driven correctly from the engine API:-

a) Calling EvpDelete() will fail, as it requires the item is in the
   Alive state.

b) Calling EvpStore(<zero-length-item>, DocState:Deleted) will
   succeed, but results in a memory leak from couchstore when fetching
   the zero-length body. Note: this is a latent bug - see MB-23697.

As such this transition isn't currently handled.

Change-Id: I9ed79e5dd1bc0387fa39a84cd5574a38d696576a
Reviewed-on: http://review.couchbase.org/76110
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: Jim Walker <jim@couchbase.com>