[avalanche] Increase mock time delay for addr responses in abc_p2p_getavaaddr

Summary:
The current delay isn't large enough. The chance that the next addr send time is longer than 300s
is roughly 1 in 22,000. We run abc_p2p_getavaaddr between 200 and 500 times per week and
wait_until(requester.addr_received) is called 4 times per test run which gives 800 to 2000 calls
per week. So even at the lower end of activity, we can expect to hit this at least once per month.

This patch increases the mock time step to actually be very unlikely, at roughly 1 in 485,000,000.

Test Plan:

./test/functional/test_runner.py abc_p2p_getavaaddr

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D12016