LU-1625 test: reduce test duration for nfs mode

LU-1625 test: reduce test duration for nfs mode

There isn't much value to run long duration in nfs mode.
Cut down IOR test as well.
Based on original work by Minh Diep.

port of patch f518a40d96d3431f3d68de9eac99ea33498894c7
port of patch e69d9852bc095695ceecb219b84bd8a48d5aa10c

Test-Parameters: envdefinitions=SLOW=yes,ENABLE_QUOTA=yes \
testlist=parallel-scale-nfsv3,parallel-scale-nfsv4

Signed-off-by: Keith Mannthey <keith@whamcloud.com>
Change-Id: I308d2dcedcb86bbc86b3d2b875e91ceeb2b96f6e
Signed-off-by: Liu Ying <emoly.liu@intel.com>
Reviewed-on: http://review.whamcloud.com/4949
Reviewed-by: Jian Yu <jian.yu@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Li Wei <wei.g.li@intel.com>
Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>