API council feedbacks for DnsResolver

To address the API review feedback provided by
the API council.

Bug: 129261432
Test: atest DnsResolverTest

Merged-In: I5737cf293264bf9d492e7bd56b62bee4d49002eb
(cherry picked from commit dca57c2e44573b330d6c6a7bf343fa74e82904f4)

Change-Id: I429dd93285f50314e9d757f4ec8539a3ba40e61b
3 files changed
tree: dddf8e6648f2b9951427258403bcd29fc33b595d
  1. core/
  2. services/
  3. tests/