[Test] DNS query blocked by UID network restrictions

Test is conducted on 4 DNS entrances over private DNS only. There is no
effective way to know whether a DNS query is rejected by the DNS
resolver or by the BPF program in kernel. However, private DNS queries
will not be rejected by BPF programs before the "DNS query fail-fast"
feature, and will be rejected after the implementation. So we use
private DNS to verify the functionality.

Bug: 288340533
Test: atest resolv_integration_test
Change-Id: Ie4a18995826a4bd7705d71b12a2af91f895ba683