LU-5842 tests: reduce time to run sanity-sec tests 13 and 14

For nodemap testing, instead of running through all possible IPs in
a NID range, just test a subset in order to verify functionality.

Signed-off-by: Kit Westneat <kit.westneat@gmail.com>
Change-Id: I4b3ec0b47b81b2d3b5ac6f4b716a13ab34c9a4c3
Reviewed-on: http://review.whamcloud.com/12532
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>