[net] Remove CConnman::Options.m_asmap

Summary:
This data member was introduced in ec45646de9e but never used.

This is a backport of core#22911 [1/4]
https://github.com/bitcoin/bitcoin/pull/22911/commits/07a9eccb60485e71494664cc2b1964ae06a3dcf0

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10779