Remove extra mockscheduler call in abc_p2p_getavaaddr

Summary: The scheduler is already mocked repeatidily to ensure the expected condition is met. Calling it one more time might change the status and break the expectation, causing the test to fail.

Test Plan:

./test/functional/test_runner.py abc_p2p_getavaaddr

Reviewers: #bitcoin_abc, roqqit

Reviewed By: #bitcoin_abc, roqqit

Differential Revision: https://reviews.bitcoinabc.org/D17679