refactor: elcontracts.ChainWriter.RegisterAsOperator

[ricomateo]

The RegisterAsOperator method in the elcontracts.ChainWriter receives an operator parameter which suggests that this is the operator being registered.

However this method calls the function registerAsOperator from the DelegationManager, which registers the caller of the function (not the operator parameter) as an operator on EigenLayer.

This can lead to confusion as users might expect the function to register the address given by the operator parameter and not the caller of the transaction.