community/xapian-core: attempt to enable tests on all arches again
By default, the xapian-core test suite contains several tests which depend heavily on timing (e.g. qp_scale1) these tests tend to occasionally fail on some architectures depending on load etc. To workaround that, disable these timing tests for now.
I only debugged this on s390x but I believe there is a high chance that this was also the failure mode observed on the other architectures.