LU-12622 tests: skip sanity test_816 with SSK

LU-12622 tests: skip sanity test_816 with SSK

sanity test_816 is incompatible with SSK, so skip it
in case SHARED_KEY is true.

Whamcloud-bug-id: ATM-1283
Test-Parameters: trivial
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I019cf6a4bab8b0cf9825b7c49f364225d5156dfa
Reviewed-on: https://review.whamcloud.com/35664
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>