test: Misc cleanup for p2p_blockfilters
Summary:
- Replace wait_until with assert_equal where possible
- Use send_and_ping helper where possible
This is a backport of core#22311 [3/4]
https://github.com/bitcoin/bitcoin/pull/22311/commits/faa211fc6e3d4984b8edff1d762dd4cba205d982
Depends on D11444
Test Plan: test/functional/test_runner.py p2p_blockfilters
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D11445