LU-11171 tests: set parameters for racer_on_nfs

LU-11171 tests: set parameters for racer_on_nfs

The parallel-scale-nfs script calls the racer test without
specifying a directory to create files, create directories,
etc. in. In addition, racer needs a few other global
parameters to work properly, including the number of OSTs,
MDTs and which LFS to use.

Test-Parameters: trivial testlist=parallel-scale-nfsv3,parallel-scale-nfsv4
Signed-off-by: James Nunez <jnunez@whamcloud.com>
Change-Id: Ic4f5f08ddec7a8df5cb818b434aa3473f6cd72cb
Reviewed-on: https://review.whamcloud.com/32880
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-by: Wei Liu <sarah@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>