Prysm V4: Remove Prysm Remote Signer

[james-prysm]

What type of PR is this?

Remove Remote Signer

What does this PR do? Why is it needed?

Prysm Remote Signer hasn't been supported well since last year before the merge. All client teams have since switched to supporting the web3signer interface. This PR attempts to fully remove the Prysm Remote Signer which is gRPC based from the repo clearing up some logic required in the setup.

Depends on #11857
Part of #11841

Which issues(s) does this PR fix?

Fixes #11700

[potuz]

Unless it's completely distinctional and dangerous to use, can we wait on this one a few weeks to see if someone voices over?
Cc @prestonvanloon

[james-prysm]

@potuz yes we can wait, this depends on web3signer tls as well. would be good for v4 though.

[terencechain]

The code looks good to me. One question I have is how early we should be warning users about this type of breaking change. Typically we should give them at least a release or more advanced time to prepare. That it goes from deprecate warning -> fully delete

[james-prysm]

The code looks good to me. One question I have is how early we should be warning users about this type of breaking change. Typically we should give them at least a release or more advanced time to prepare. That it goes from deprecate warning -> fully delete

unlike the webui i don't think anyone is currently using this, as it hasn't been updated since before the merge and we only offered a prototype implementation. so I think coinbase was the last user of this feature.
#11700 also opened this in november. I wanted to defer to preston if he knew more but if we want to put another notice before merging I am ok with that decision too...

[rauljordan]

Ok with this is v4 is the next release. Otherwise, we might want to make sure to deprecate instead of deleting