LU-8248 tests: fix sanity test_248 VM checks

LU-8248 tests: fix sanity test_248 VM checks

Skip test on clients that do not have fast_read support.
If running in any VM, not just kvm, ignore perf test failures.

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: I09fbdb58e71d042c57b6bac1f6f1ef82243ebbe5
Reviewed-on: http://review.whamcloud.com/20698
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>