Missing 1 bitcoin block download causes subsequent blocks to fail

[MicaiahReid]

Sometimes when the Chainhook service receives a new_burn_block, it then fails to download the block.

I'm not entirely sure why this happens, as the same block will be downloaded (at pretty much the exact same time) by Ordhook.

But, when this does happen, because we have a gap in our fork pool, we fail to append all future bitcoin blocks. We should:

1. increase the number of retries when downloading a block
2. auto-restart chainhook if we fail to download a block