Pull request ElementsProject/lightning#4499

Expand dual-funded path test coverage

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Range Diff Matrix


6619..6649
6619..6650	6649..6650
6619..6666	6649..6666	6650..6666
6619..6667	6649..6667	6650..6667	6666..6667
6619..6678	6649..6678	6650..6678	6666..6678	6667..6678
6619..6679	6649..6679	6650..6679	6666..6679	6667..6679	6678..6679