[mobile] Skip DnsGetHostEntry_LocalHost test on Android (#127420)

> [!NOTE]
> This content was generated by GitHub Copilot.

## Summary

Fixes
`System.Net.NameResolution.Functional.Tests.GetHostEntryTest.DnsGetHostEntry_LocalHost_ReturnsFqdnAndLoopbackIPs`
test failure on Android by skipping the test on that platform.

## Background

The test assumes that resolving "localhost" returns only loopback IP
addresses (`127.0.0.1` and `::1`). However, on Android Helix machines
(emulators), the DNS resolution for "localhost" returns actual network
interfaces in addition to loopback addresses, causing the test to fail
with assertions like:

`````
Assert.All() Failure: 5 out of 6 items in the collection did not pass.
[1]: Item:  fe80::e05a:f2ff:fee9:6ae6%47
     Error: Not a loopback address: fe80::e05a:f2ff:fee9:6ae6%47
[2]: Item:  2001:4898:502:2:e05a:f2ff:fee9:6ae6
     Error: Not a loopback address: 2001:4898:502:2:e05a:f2ff:fee9:6ae6
[5]: Item:  10.64.32.211
     Error: Not a loopback address: 10.64.32.211
````

## Changes

Added `[SkipOnPlatform(TestPlatforms.Android, ...)]` attribute to the
failing test, consistent with existing skips for iOS, tvOS, and
MacCatalyst on the same test (which have similar issues).

## Failure Details

**Build:**
https://dev.azure.com/dnceng-public/public/_build/results?buildId=1396313

**Job:** `android-arm64 Release AllSubsets_Mono`

**Helix Work Item:** System.Net.NameResolution.Functional.Tests
- Job ID: `93091357-214b-436d-a5c4-a31ee456a876`
- Console log:
https://helix.dot.net/api/2019-06-17/jobs/93091357-214b-436d-a5c4-a31ee456a876/workitems/System.Net.NameResolution.Functional.Tests/console

**Log excerpt (sanitized):**
````
04-25 00:03:35.029  DOTNET  : [FAIL] System.Net.NameResolution.Tests.GetHostEntryTest.DnsGetHostEntry_LocalHost_ReturnsFqdnAndLoopbackIPs(mode: 0)
04-25 00:03:35.029  DOTNET  : Assert.All() Failure: 5 out of 6 items in the collection did not pass.
04-25 00:03:35.029  DOTNET  : [5]: Item:  10.64.32.211
04-25 00:03:35.029  DOTNET  :      Error: Not a loopback address: 10.64.32.211
`````

## Related

- Existing skip on iOS/tvOS/MacCatalyst: #124079
- Similar Wasi skip: #107339




> [!NOTE]
> <details>
> <summary>🔒 Integrity filter blocked 1 item</summary>
>
> The following item were blocked because they don't meet the GitHub
integrity level.
>
> - [#126805](#126805)
`search_pull_requests`: has lower integrity than agent requires. The
agent cannot read data with integrity below "approved".
>
> To allow these resources, lower `min-integrity` in your GitHub
frontmatter:
>
> ```yaml
> tools:
>   github:
>     min-integrity: approved  # merged | approved | unapproved | none
> ```
>
> </details>


> Generated by [Mobile Platform Failure
Scanner](https://github.com/dotnet/runtime/actions/runs/24929356562/agentic_workflow)
· ● 4.1M ·
[◷](https://github.com/search?q=repo%3Adotnet%2Fruntime+%22gh-aw-workflow-id%3A+mobile-scan%22&type=pullrequests)

<!-- gh-aw-agentic-workflow: Mobile Platform Failure Scanner, engine:
copilot, model: claude-sonnet-4.5, id: 24929356562, workflow_id:
mobile-scan, run:
https://github.com/dotnet/runtime/actions/runs/24929356562 -->

<!-- gh-aw-workflow-id: mobile-scan -->

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: kotlarmilos <11523312+kotlarmilos@users.noreply.github.com>

Author: 4 people

src/libraries/System.Net.NameResolution/tests/FunctionalTests/GetHostEntryTest.cs

@@ -260,7 +260,7 @@ public async Task DnsGetHostEntry_BadName_ThrowsArgumentOutOfRangeException_Obso
         [InlineData(1)]
         [InlineData(2)]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/107339", TestPlatforms.Wasi)]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/124079", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/124079", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst | TestPlatforms.Android)]
         public async Task DnsGetHostEntry_LocalHost_ReturnsFqdnAndLoopbackIPs(int mode)
         {
             IPHostEntry entry = mode switch