test: Avoid logging error when logging error

[maflcko]

Currently a logging error in the form of --- Logging error --- happens when an error is logged in the _on_data helper.

Fix it by properly logging the error.

Also, treat pylint errors as errors, to avoid this problem in the future.

Can be tested by running p2p_addrv2_relay.py with the following example diff:

diff --git a/test/functional/test_framework/p2p.py b/test/functional/test_framework/p2p.py
index 523e1bd068..0f1eb29d13 100755
--- a/test/functional/test_framework/p2p.py
+++ b/test/functional/test_framework/p2p.py
@@ -137,7 +137,7 @@ MESSAGEMAP = {
     b"notfound": msg_notfound,
     b"ping": msg_ping,
     b"pong": msg_pong,
-    b"sendaddrv2": msg_sendaddrv2,
+    #b"sendaddrv2": msg_sendaddrv2,
     b"sendcmpct": msg_sendcmpct,
     b"sendheaders": msg_sendheaders,
     b"sendtxrcncl": msg_sendtxrcncl,

[DrahtBot]

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For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/31408.

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ACK	fanquake

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[fanquake]

ACK cccca8a