[backport#18726] test: check misbehavior more independently in p2p_filter.py
Summary:
cd543d9193ac1882c1b4a8a84e3ac7356a8b7ce9 test: check misbehavior more independently in p2p_filter.py (Danny Lee)
Pull request description:
This expands on #18672 in two ways: - Check positive cases (`filterload` accepted, `filteradd` accepted) in addition to the negative cases added in #18672 - Address MarcoFalke 's [suggestion](https://github.com/bitcoin/bitcoin/pull/18672#discussion_r412101752) to successfully load a filter before testing `filteradd`
Backport of Core PR18726
Test Plan:
ninja all check check-functional
Reviewers: #bitcoin_abc, PiRK
Reviewed By: #bitcoin_abc, PiRK
Differential Revision: https://reviews.bitcoinabc.org/D9092