Merge pull request #2534 from tnull/2023-08-upstream-preflight-probing

Upstream and fix preflight probing

diff --cc fuzz/src/chanmon_consistency.rs
Simple merge

diff --cc lightning-background-processor/src/lib.rs
Simple merge

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

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

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

diff --cc lightning/src/routing/scoring.rs
Simple merge