[avalanche] Pass our local proof to the peer manager at construct time

Summary:
This avoid having to pass it at each call where it's needed, since it can't change without a reboot.

Depends on D14670.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D14679