LU-3262 tests: add slow ost-pools tests to SLOW list

LU-3262 tests: add slow ost-pools tests to SLOW list

Add test 5b, 18, 22, and 25 to the SLOW list, which cuts about
30 minutes off the ost-pools test time if run with SLOW=no.

Test-Parameters: testlist=ost-pools,ost-pools,ost-pools
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: I430bdf5132516351e345df3ccf5461cb62500c1e
Reviewed-on: http://review.whamcloud.com/6235
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Emoly Liu <emoly.liu@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>