Bump the timeout in p2p_ibd_stalling
Summary: This test fails regularly to receive the block data before the timeout triggers on our slow osx CI machine.
Test Plan:
./test/functional/test_runner.py p2p_ibd_stalling
Reviewers: #bitcoin_abc, roqqit
Reviewed By: #bitcoin_abc, roqqit
Differential Revision: https://reviews.bitcoinabc.org/D17586