[test] [rhel8] adjust check for non-UBI RPMs in containers

The behave test suite includes a check that the final container images do not include a set of RPMs that are known to be soft dependencies of OpenJDK but are not in the set of packages distributed under the UBI EULA. This can happen with internal build processes if misconfigured.

The package dejavu-sans-mono-fonts is in this list but has since migrated into the UBI set. Thus, the tests are failing.