[net] remove CConnman::SetServices

Summary:

It just forwards calls to CAddrMan::SetServices.

Partial backport of core#20228:
https://github.com/bitcoin/bitcoin/pull/20228/commits/8073673dbcb2744fcc9c011edf2d61388ca929cd

Depends on D12247.

Test Plan:

ninja all check

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Subscribers: PiRK

Differential Revision: https://reviews.bitcoinabc.org/D12248