In the case of the headers message, there is a message size limit related to the number of headers that kicks in about one order of magnitude below the message sizes being tested here (80 bytes * 2000 headers =160000 bytes) . When inspecting the log, you can see that the following lines are being logged, showing that the node actually rejects these message sizes:
```
Misbehaving: peer=0 (0 -> 20): too-many-headers: headers message size = 2097146
Misbehaving: peer=0 (0 -> 20): too-many-headers: headers message size = 1999996
Misbehaving: peer=0 (0 -> 20): too-many-headers: headers message size = 999996
```
So contrary to the intent of the test, the tested network messages are no in fact "not_oversized_msg".
In a future diff the misbehavior score increment will be bumped from 20 to 100, and the peer will actually be disconnected, which would cause the removed tests to fail on `conn.send_and_ping`.
See D16343 for why these tests where added.
Depends on D18025