Rebroadcast Bug

Our current flow of rebroadcasting finalize votes could cause a safety failure.

Say we finalize `b3` which belongs to this chain of blocks. `b1 <- b3`(we have not yet finalized `b1`. However, our node has a notarization for `b2`. In our current logic, we would create a finalize vote for `b2` and broadcast it. In fact a quorum of nodes had `b2` notarized, but the block proposer build off the empty notarization in `b2`. We could end up creating a finalization for `b2` which would be the same sequence as `b3`.