If TxLock does not confirm in a reasonable amount of time, Alice should
give up on the swap rather than waiting forever. Watching for TxLock in
the mempool is not required and it causes unnecessary complexity. What
if Alice does not see the transaction in mempool but it is already
confirmed? She will abort the swap for no reason.
We define the sync interval as 1/10th of the blocktime. For the
special case of our tests, we however check at max once per second.
The tests have a super fast blocktime. As such we shouldn't hammer
the nodes with a request every 100ms.
