Adapt for new parameterization

Created by: zarubaf

Companion commit to https://github.com/openhwgroup/cva6/pull/1321.

It deprecates the top-level ArianeCfg config struct in favor of the CVA6 one. Furthermore, the testbench now defaults to the Default config struct in the ariane_pkg. While that isn't super useful for reproducibility, this should ideally limit the changes to coer-v-verif at the moment. Once the config struct is stable a "known-good" configuration can be fixed here.