[avalanche] Optimize block parking

Summary:
Leverage the avalanche finalized block index to park blocks. This will allow us to remove -parkdeepreorg
in the future.

Depends on D12885

Test Plan:

ninja check check-functional

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D12886