80a5e59 [qa] Attach node index to test_node AssertionError and print messages (James O'Beirne)
Pull request description:
In the midst of fighting with https://github.com/bitcoin/bitcoin/pull/12873 it became apparent that there're a number of assertions and print statements which are emitted by test nodes but don't identify the node in question. This change makes debugging a bit easier by adding identifying information to non-logger test_node-related error messages.
Backport of Core PR13022
Depends on D3914