LU-7372 tests: disable replay-dual test_26

LU-7372 tests: disable replay-dual test_26

This test is continually failing, preventing replay-dual from being
re-enabled during normal review testing.  Disable it for now so that
we can return replay-dual to normal review test coverage.

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: Ib7129ccbf48197a31bedd8f37ea63fd9038cab07
Reviewed-on: http://review.whamcloud.com/20669
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>