Build the CUUP on the cluster and minor Dockerfile fixes
- Build the CUUP on the cluster (but not used yet, is for @arora)
- Rename the Dockerfile for gNB-AW2S to
*ubuntu20
(because it is based on U20) - Remove rfsimulator from cuup images: it does not make sense, the CUUP has E1/F1-U/NG-U terminations, but not rfsimulator