Remove USE_NETWORK_INSTANCE for SMF on all docker-compose and helm chart files

Description

After SMF MR !169 is merged, we don't need the USE_NETWORK_INSTANCE parameter anymore.

@defosseu I have removed the value from all the docker-compose files, the config files and the helm chart values, but I have not removed it from docs/results/dsTest/*. Is this part of the repo still updated? It looks outdated, e.g., the SMF IP pool configuration.

Tests

I have manually tested gnbsim attach and ping for all changed docker-compose files. docker-compose-basic-vpp-nonrf.yaml fails, because of a wrong DNN config (see also comment in MR !88 (closed).

@arora I did not test with Kubernetes. Can you check if it still works?