Fix and restore the disconnects_from_misbehaving_peers test

[arya2]

Motivation

This test was commented out as it was causing CI failures due to a concurrency bug.

It's important test coverage that should be restored ahead of zcashd deprecation.

This issue could also track extending the test to check for the expected behaviour for every variant of errors with a misbehavior_score() or mempool_misbehavior_score() method.