The test as it stands today does not make sense as it adds a
Partial/Shell node to the graph via AddLightningNode which will never
happen since this is only ever triggered by the gossiper which only
calls the method with a full node announcement. Shell/Partial nodes are
only ever added via AddChannelEdge which will insert a partial node if
we are adding a channel edge which has node pub keys that we dont have a
node entry for. So we adjust the test to use this more accurate flow.
Elle Mouton
4131b3fc7e