LU-1213 tests: remove duplicate parallel-scale variables

LU-1213 tests: remove duplicate parallel-scale variables

Remove the duplicate variables from parallel-scale.sh and
parallel-scale-nfs.sh. Those variables are defined inside
the corresponding functions in functions.sh.

Signed-off-by: Yu Jian <yujian@whamcloud.com>
Change-Id: I77ea061289296aeb8b138631f7a55090f52093c9
Reviewed-on: http://review.whamcloud.com/2306
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Cliff White <cliffw@whamcloud.com>
Reviewed-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>