[validation] merge all ConnectBlock debug logging code paths

Summary:
This concludes backport of core#31112
https://github.com/bitcoin/bitcoin/pull/31112/commits/492e1f09943fcb6145c21d470299305a19e17d8b
Depends on D18879

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D18880