auctioneer: Do not allow searchers to send transactions when optimistic block height deviates from the soft block height

[bharath-123]

Rationale

The optimistic block height should be always one block ahead of the soft block at any given time. If there is an issue with the optimistic block execution, we will be validating txs in the mempool on a stale optimistic block which is not desirable.
We need to disallow searchers from sending transactions via the eth_sendRawTransaction and eth_sendTransaction json-rpc methods if the deviation between optimistic block and soft block is more than 2.