test: update the funding test to use new async updates/notifications
test: update the funding test to use new async updates/notifications

This commit increases the robustness of the current test and also
reduces it’s running time considerably as all “time.Sleep”s have now
been removed.

Rather than sleeping some random amount of time, the test now waits for
a particular async notification to be dispatched before proceeding.
This tightens up the execution of the tests quite a bit.

LightningNetwork/lnd,ddustin/lnd,LightningNetwork/lnd,bryanvu/lnd,ddustin/lnd,AndrewSamokhvalov/lnd,bryanvu/lnd,aakselrod/lnd,aakselrod/lnd,AndrewSamokhvalov/lnd