fa3e9f7627 qa: Add TestNode::assert_debug_log (MarcoFalke)
Pull request description:
Closes #13006
Tree-SHA512: 8e2d2331039d70525a425aad65a4eaf9b83fb1f85a4260d69453176f04dbede6dd9b7bb4d5f089b46cf8f8c98571aa6ba7fac8fa6847bb3bdf6a6ad21a27b1a7
Backport of Core PR14024
https://github.com/bitcoin/bitcoin/pull/14024/files