[avalanche] Fix extended tests that use buildavalancheproof

Summary:
The tests were missed in D10092.

Ref T1676.

Test Plan:

./test/functional/test_runner.py abc_p2p_proof_inventory p2p_inv_download

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Maniphest Tasks: T1676

Differential Revision: https://reviews.bitcoinabc.org/D10103