Disable localhost subdomain AddressFamily tests on Android

[rzikm]

Disables DnsGetHostEntry_LocalhostSubdomain_RespectsAddressFamily and DnsGetHostAddresses_LocalhostSubdomain_RespectsAddressFamily on Android using [ActiveIssue].

Problem

These tests (introduced in #123076 for RFC 6761 localhost subdomain handling) consistently fail on Android CI (windows.11.amd64.android.open):

System.Net.Sockets.SocketException : hostname nor servname provided, or not known
   at System.Net.Dns.GetHostEntryOrAddressesCore(...)
   at System.Net.Dns.GetHostEntryOrAddressesCore(...)  // fallback for "localhost"
   at System.Net.Dns.GetHostEntryCore(...)
   at System.Net.Dns.GetHostEntry(...)

The tests call e.g. Dns.GetHostEntry("test.localhost", AddressFamily.InterNetwork). The RFC 6761 implementation tries the OS resolver for "test.localhost" first, then falls back to resolving "localhost" with the same AddressFamily. On Android, getaddrinfo("localhost", ..., AF_INET/AF_INET6) may fail with EAI_NONAME while getaddrinfo("localhost", ..., AF_UNSPEC) succeeds — causing both the initial and fallback resolution to fail.

Other localhost subdomain tests that use AddressFamily.Unspecified (e.g. ReturnsLoopback) pass on Android.

Example console log: https://helixr1107v0xdeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-heads-main-76f79e897d5246b58a/System.Net.NameResolution.Functional.Tests/1/console.858b3560.log?helixlogtype=result

Contributes to #124751

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[Copilot]

Pull request overview

Disables two System.Net.NameResolution functional tests that validate *.localhost subdomain resolution with AddressFamily filtering on Android, due to consistent CI failures tied to Android resolver behavior.

Changes:

• Mark DnsGetHostEntry_LocalhostSubdomain_RespectsAddressFamily as skipped on Android via [ActiveIssue].
• Mark DnsGetHostAddresses_LocalhostSubdomain_RespectsAddressFamily as skipped on Android via [ActiveIssue].

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/libraries/System.Net.NameResolution/tests/FunctionalTests/GetHostEntryTest.cs	Adds [ActiveIssue(..., TestPlatforms.Android)] to disable the AddressFamily localhost-subdomain test on Android.
src/libraries/System.Net.NameResolution/tests/FunctionalTests/GetHostAddressesTest.cs	Adds [ActiveIssue(..., TestPlatforms.Android)] to disable the AddressFamily localhost-subdomain test on Android.