[SSSD] [PATCH] CI: Enforce coverage make check failures

[Nikolai Kondrashov]

Hi everyone,

The attached patch enforces make check failures for the CI coverage build, so
we can catch more test failures.

I think this should also be applied onto sssd-1-12.

NOTE: CI won't pass with this patch ATM, as test_ipa_subdom_server needs to be
       fixed first.

Nick