htlcswitch/link_test: update Bandwidth tests
htlcswitch/link_test: update Bandwidth tests

This commit updates the tests for checking a links Bandwidth()
calculation, after the change that made us use the remoteACKedIndex
instead of the logIndex when calculating it. The main result of this
change is that we never consider incoming updates before they are
acked, when calculating the bandwidth. This is because this was
inconsistent with the state we actually end up signing later on.

aakselrod/lnd,LightningNetwork/lnd,aakselrod/lnd,LightningNetwork/lnd