Switch to listening for all network changes.

This is for use while preferred upstreams are expressed as legacy types.

Test: as follows
    - built (bullhead)
    - flashed
    - booted
    - runtest frameworks-net passes
    - USB tethering to WiFi and DUN works
Bug: 32163131
Change-Id: I76e7b6c95eb1b54e926096b2791163617bb0a818