[avalanche] Simplify the wait_for_proof test facility
Let it take the expected status rather than flagging the orphan special case. This makes the tests more robust as we are sure of what is being tested.
Depends on D11802.
ninja all check-extended
Reviewers: #bitcoin_abc, sdulfari
Reviewed By: #bitcoin_abc, sdulfari
Differential Revision: https://reviews.bitcoinabc.org/D11809