[bug]: EstimateRouteFee alters the destination for public nodes leading to inaccurate estimations.

[ziggie1984]

Some lightning implementations (CLN) add routehints to the invoice to signal where they have liquidity on the incoming channel. Our current estimateroutefee rpc call will alter the route and try to send a payment to the pre-last hop, messing up the fee-estimation.

Not 100% sure what was the main assumption behind the isLSP heuristic we have in the code, but we need to make sure that public node destinations are excluded and probed directly instead of altering the route.