`resolve_rh_variant_prod_comp_cdx_external_reference_ancestors` fails when cache is not primed

Test `resolve_rh_variant_prod_comp_cdx_external_reference_ancestors` fails when the cache is not primed. I think this points in the direction of https://github.com/guacsec/trustify/pull/2118 and https://issues.redhat.com/browse/TC-3170