rpc: remove deprecated getaddressinfo fields

Summary:

rpc: remove deprecated getaddressinfo label field

rpc: remove deprecated getaddressinfo labels: purpose

rpc: getaddressinfo RPCResult fixup

doc: release note for rpc getaddressinfo removals

This is a backport of core#19200

Depends on D9609

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, majcosta, Mengerian

Reviewed By: #bitcoin_abc, majcosta, Mengerian

Subscribers: Mengerian, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D9622