LU-6082 tests: fix too slow nodemap SLOW test

LU-6082 tests: fix too slow nodemap SLOW test

The SLOW test for nodemap is too slow to complete. This patch changes
the test to do 000-007, 010-070, 100-700 (octal) instead of testing
all modes, as was done before.

Test-Parameters: alwaysuploadlogs envdefinitions=SLOW=yes \
mdtfilesystemtype=ldiskfs mdsfilesystemtype=ldiskfs ostfilesystemtype=ldiskfs \
mdtcount=1 testlist=sanity-sec

Signed-off-by: Kit Westneat <kit.westneat@gmail.com>
Change-Id: Ic92a3718de078ccfd13cf0b6580ab078dfedb144
Reviewed-on: http://review.whamcloud.com/13605
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>