test: Re-ignore SELinux messages about op=security_compute_av
test: Re-ignore SELinux messages about op=security_compute_av

This got removed in commit bdcfa44913 but now hits the RHEL 7.5 images
again with full force. As  this affects all tests, this is impractical
for a naughty override.

See https://bugzilla.redhat.com/show_bug.cgi?id=1461893

Closes #8538

deryni/cockpit,garrett/cockpit,moraleslazaro/cockpit,andreasn/cockpit,SotolitoLabs/cockpit,SotolitoLabs/cockpit,cockpituous/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,mareklibra/cockpit,garrett/cockpit,stefwalter/cockpit,andreasn/cockpit,cockpituous/cockpit,andreasn/cockpit,moraleslazaro/cockpit,stefwalter/cockpit,SotolitoLabs/cockpit,mvollmer/cockpit,cockpit-project/cockpit,mareklibra/cockpit,martinpitt/cockpit,stefwalter/cockpit,mareklibra/cockpit,martinpitt/cockpit,SotolitoLabs/cockpit,mvollmer/cockpit,SotolitoLabs/cockpit,stefwalter/cockpit,cockpituous/cockpit,deryni/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,andreasn/cockpit,cockpit-project/cockpit,deryni/cockpit,martinpitt/cockpit,garrett/cockpit,martinpitt/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,mareklibra/cockpit,deryni/cockpit,SotolitoLabs/cockpit,andreasn/cockpit,mareklibra/cockpit,garrett/cockpit,deryni/cockpit,cockpit-project/cockpit,andreasn/cockpit,moraleslazaro/cockpit,stefwalter/cockpit,stefwalter/cockpit,garrett/cockpit,mvollmer/cockpit,mareklibra/cockpit,deryni/cockpit,cockpit-project/cockpit,deryni/cockpit,mvollmer/cockpit,SotolitoLabs/cockpit,mareklibra/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpituous/cockpit,andreasn/cockpit,stefwalter/cockpit