[backport#17850] Convert addrdb/addrman to new serialization

Summary:
The review for the change in src/addrdb.h needs to take into account the fact that PR19129 was merged before PR17850.
See 2ad5838 and D7146.

This is a backport of Core PR17850 [2/2]
https://github.com/bitcoin/bitcoin/pull/17850/commits/9250a087d2f450f37342010aea0a5d583eea508b

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D8392