Use async dns query to resolve all addresses

Currently, it looks like private DNS server resolution uses
OneAddressPerFamilyNetwork and only returns one server address.
It should return all addresses. Use async dns api for this.

Bug: 123435238
Test: atest NetworkStacktests

Change-Id: I2b7e184d9b9800a83b55dceb73af69085668748c
(cherry picked from commit 40c5295c)
Merged-In: I2b7e184d9b9800a83b55dceb73af69085668748c
Merged-In: I9f50da3c8c2e3b12b29bc8844291e4bf1559cd1f