[avalanche] Add the finalized transactions ancestors to the list of recently finalized items

Summary: So we don't keep polling for ancestors when the child tx has been finalized.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, PiRK, roqqit

Reviewed By: #bitcoin_abc, PiRK, roqqit

Subscribers: PiRK

Differential Revision: https://reviews.bitcoinabc.org/D17751