EX-3676 tests: skip conf-sanity test_5a

EX-3676 tests: skip conf-sanity test_5a

Skip conf-sanity test_5a since it is causing constant failures since
/sbin/umount.lustre was added.

Test-Parameters: trivial testlist=conf-sanity env=ONLY=1-5 \
austeroptions=-H
Fixes: 6d62073950ac ("EX-3209 lipe: add lpcc util and service")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I77531407d02c5accc78fc239f65c4d05d995502f
Reviewed-on: https://review.whamcloud.com/44839
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>