Currently if an observation hasn't reached quorum within 5 minutes, the
processor will re-broadcast the signed local observation to the other
guardians in the network. However if not enough guardians actually
observed the original tx, then no amount of re-broadcasting will help
the network reach quorum.
Fix this issue by sending a re-observation request whenever we
re-broadcast a signed local observation. This ensures that any
guardians that missed the tx the first time it happened have a chance to
re-observe it and help the network reach quorum.
1753bb34f0