CLI: reconsider gossamer init

## Issue summary

Is `gossamer init` pointless? Shall we remove it?

Gossamer cli currently supports inputs from
- Flags
- A toml config file
and we could support ENVs in the future.

If I am working with a config file(which I won't, terraform + ansible is the top choice!), I'd prefer to generate the config file, understand the various fields and then run the node. One could also prefer to have pre-built config files and feed them as input through ansible scripts.

There was an earlier discussion on renaming the `gossamer init` to `gossamer config-init` for this purpose #3171. It wasn't handled at the time since this change affects a lot of integration-tests.