We recently ran a large-block experiment on the testnet and plan to do a further experiment on mainnet.
Although the metrics recovered from lighthouse nodes were quite useful, I think we could do with greater resolution in the block delay metrics and get some specific values for each block (currently these can be lost to large exponential histogram buckets).
This PR increases the resolution of the block delay histogram buckets, but also introduces a new metric which records the last block delay. Depending on the polling resolution of the metric server, we can lose some block delay information, however it will always give us a specific value and we will not lose exact data based on poor resolution histogram buckets.
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