Improve test for the changing of DnsResolver

1. Done for some code-style nits.
2. Update tests because AnswerCallback of DnsResolver is changed.

Bug: 124882626
Test: built, flashed, booted
      atest DnsResolverTest

Change-Id: Ie862c7ea5077f56fd9a4d96baf3f466b65db93d8
1 file changed
tree: 3f83465edb82ccaae4ac73828745bc0e8711c607
  1. tests/