test: Add more tests for orphan tx handling
Summary:
This PR adds test coverage for the following cases: - erase orphan transactions when a peer is disconnected - erase an orphan transaction when it is included in a new tip block - erase an orphan transaction when it is conflicted with other transactions included in a new tip block
Backport of core#19393.
Test Plan:
./test/functional/test_runner.py p2p_invalid_tx
Reviewers: #bitcoin_abc, PiRK
Reviewed By: #bitcoin_abc, PiRK
Differential Revision: https://reviews.bitcoinabc.org/D16502