LU-4515 tests: set fail_loc only once per node

LU-4515 tests: set fail_loc only once per node

Since fail_loc and fail_val are common for all services on a node,
it is only necessary to set it once per node instead of once per
facet.  That avoids a bunch of extra remote commands and spew in
the test output.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: I9a69eb325fa80a90d929ab9a258cce21973ebbe5
Reviewed-on: http://review.whamcloud.com/8978
Tested-by: Jenkins
Reviewed-by: Faccini Bruno <bruno.faccini@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>