Use custom defined DNS/HTTP port

Refactor the test case to support listen custom DNS/HTTP port.
Avoid binding system restricted port (<1024).

Bug: 322113686
Test: atest NetworkStackIntegrationTests:android.net.NetworkStatsIntegrationTest
Change-Id: I5d3b966cdadc9321ca2ee0d04a5b8f71ee79bd8a
5 files changed