Merge pull request #2590 from TheBlueMatt/2023-09-default-score-params

Use `Default::default()` to construct `()` as a test scoring param

diff --cc lightning/src/ln/channelmanager.rs
Simple merge

diff --cc lightning/src/ln/functional_test_utils.rs
Simple merge

diff --cc lightning/src/ln/functional_tests.rs
Simple merge

diff --cc lightning/src/ln/payment_tests.rs
Simple merge