fix(consensus): Check Equihash solutions with n=200, k=9 parameters

[arya2]

Motivation

This always checks Equihash solutions with the Mainnet/Testnet parameters, even if Zebra receives a block with a shorter Equihash solution. This is fine for Regtest for now since it skips the Proof-of-Work check altogether.

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Solution

• Reverts a change that allows for validating Equihash solutions with easier parameters on Mainnet and Testnet

Review

Anyone can review.

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Follow Up Work

Add a field on testnet::Parameters for defining a network's Equihash parameters