cab0824 Logprint the start of a rescan (Jonas Schnelli)
Pull request description:
Right now, there is no log entry when a rescan starts which is confusing especially when a "still rescanning" log entry appears after the log-update timeout of 60s or when user manually aborts the rescan. This PR adds a log entry when a rescan starts.
Tree-SHA512: 8712605af6fd60950bf3904cfb586da6022e44b3da6f3155fe4f02aae16df6044bc504b3d48945ea6d7fe768f0c6cb3282a2e2251d14bf3b7f1dcbd12568b05e
Backport of Core PR12925