[avalanche] Return addresses of nodes we did not poll yet

Summary:
We should not refrain from sharing addresses of nodes we did not poll, especially since we might simply not be ready for polling yet.

Ref T1696.

Depends on D11276.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, tyler-smith

Reviewed By: #bitcoin_abc, tyler-smith

Subscribers: tyler-smith

Maniphest Tasks: T1696

Differential Revision: https://reviews.bitcoinabc.org/D11277