Remove ValidatorRegistrations for Gloas

[bharath-123]

In Gloas, ProposerPreferences has been introduced to send the proposer's fee recipient, gas limit and validator index to on-chain builders for block building. These preferences are sent over the proposer_preferences gossip topic.

ValidatorRegistrations contain essentially the same information outside the BuilderPreferences.

We can expect builders to listen to ProposerPreferences for the fee_recipient, gas limit and validator index of the proposer. Per builder preferences like max_trusted_bid can be sent directly to builders. This can reduce duplicity across the builder-api and on-chain builder auction.

[nflaig]

Per builder preferences like max_trusted_bid can be sent directly to builders.

wouldn't you use the same mechanism as today to do that or how do you imagine validator would sent these to the builder? Since they need to signed by the validator there also needs to be beacon api for that similar to today

overall if we can avoid having per builder preferences it would be ideal

[bharath-123]

I have raised the question of if need builder preferences here: #152 :)

[bharath-123]

Yeah builder preferences are probably the only reason we might need a validator registration. If we remove that, then the Builder-API can become completely stateless and clean!