Remove unreliable tests.

These tests fail/not fail on a constant basis and are therefore
not reliable and lead to false positivies. They are removed for
now and can be considered to be readded later with different
implementations.

Change-Id: Ic94d7a3a2ce4cd8c17f2aeb94b57eb670e2a41a5
Reviewed-on: http://review.couchbase.org/28792
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>