Immediately Observe UTXO Outbounds After Signing

We have observed issues with reschedule due to mempool and block transaction load on UTXO chains, which can result in outbounds not being observed before the reschedule height. We should update Bifrost the immediately post an observation for the outbound after signing, to result in the reschedule height being increased by the signing period for each of the vault members which successfully post the observation.