[avalanche] Limit the remote proofs per peer

Summary:
Ensure we don't store an unbound number of proofs from our peers, but allow for expansion as the network grows.

Depends on D14660.

Test Plan:

ninja check-avalanche-peermanager_tests

Reviewers: #bitcoin_abc, PiRK, bytesofman

Reviewed By: #bitcoin_abc, PiRK, bytesofman

Subscribers: PiRK

Differential Revision: https://reviews.bitcoinabc.org/D14661