[avalanche] Factorize the inflight request timeout handling

Summary:
This diff extracts a lambda that can be used with any kind of vote items, for now blocks and proofs.

Ref T1854.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Maniphest Tasks: T1854

Differential Revision: https://reviews.bitcoinabc.org/D10384