Remove support for ropsten testnet

[peterbitfly]

What type of PR is this?
Bug fix

What does this PR do? Why is it needed?
Currently prysm does not work together with geth v1.11.0 when used as a module. This is because prysm still maintains a config for the now obsolete ropsten testnet and imports some configuration details from geth. With geth v1.11.0 this definitions were removed and now prysm breaks the following error as soon as it is imported together with geth:

# github.com/prysmaticlabs/prysm/v3/config/params
../../pkg/mod/github.com/prysmaticlabs/prysm/v3@v3.1.1/config/params/testnet_ropsten_config.go:29:34: undefined: params.RopstenChainConfig
../../pkg/mod/github.com/prysmaticlabs/prysm/v3@v3.1.1/config/params/testnet_ropsten_config.go:30:36: undefined: params.RopstenChainConfig

This PR removes the testnet_ropsten_config.go configuration file together with all ropsten configuration options.

[nisdas]

Hey @peterbitfly ,

Thanks for opening this PR, to deprecate the testnet correctly, you will need to add it to the deprecated flags list. For an example of where we do this you can look at:
#10522

[jclapis]

I'll add a +1, we just ran into this with the Rocket Pool stack. We're sticking to Geth v1.10.26 and Prysm v3.2.0 until it's resolved.

[nisdas]

@peterbitfly I was unable to push the changes to this branch, so I opened a new PR which has them here:
#12058

[nisdas]

Closing this PR as #12058 has merged in.