[backport#15750] [rpc] Remove the addresses field from the getaddressinfo return object

Summary:
The "addresses" field was confusing because it refered to public keys
using their P2PKH address. It was included in the return object when
needed for backward compatibility. Remove that compatibility now that
the -deprecatedrpc=validateaddress option has been removed.

New applications should use the 'embedded'->'address' field for P2SH or
P2WSH wrapped addresses, and 'pubkeys' for inspecting multisig
participants.

https://github.com/bitcoin/bitcoin/pull/15750/commits/b4338c151d4788c33f4b7c54daaf7f94b193a624

Backport of Core PR15750

Test Plan:

ninja check-all

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D6392