LU-4745 tests: Skip dry-run for OST version older than 2.5.56

LU-4745 tests: Skip dry-run for OST version older than 2.5.56

Skip the dry-run testing in test_52 for OST version older than
2.5.56

Test-Parameters: alwaysuploadlogs \
envdefinitions=SLOW=yes,ENABLE_QUOTA=yes,ONLY=52 \
mdtfilesystemtype=ldiskfs mdsfilesystemtype=ldiskfs \
ostfilesystemtype=ldiskfs clientdistro=el6.6 ossdistro=el6 \
mdsdistro=el6 clientarch=x86_64 ossarch=x86_64 mdsarch=x86_64 \
ossjob=lustre-b2_5 mdsjob=lustre-b2_5 \
ossbuildno=86 mdsbuildno=86 mdtcount=1 mdssizegb=3 \
ostcount=7 ostsizegb=3 testlist=conf-sanity

Change-Id: If3b45f6d29b83bce21ed40c67c5e985a8a9fd6db
Signed-off-by: Wei Liu <wei3.liu@intel.com>
Reviewed-on: http://review.whamcloud.com/9739
Tested-by: Jenkins
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>