Skip Xcode provisioning for RunOnAndroid integration tests (dotnet#34053)

RunOnAndroid integration tests run on macOS but only test Android
emulator scenarios. They were provisioning Xcode unnecessarily, wasting
~5-10 minutes per test run.

## Changes

- **`setup-test-env.yml`**: Added `skipXcode` parameter (default
`false`)
- Passes value to `provision.yml` for both `skipXcode` and
`skipSimulatorSetup`
  
- **`stage-integration-tests.yml`**: Skip Xcode for Android-only tests
  - `skipXcode: ${{ eq(job.testCategory, 'RunOnAndroid') }}`
- All other categories (Build, Blazor, MultiProject, macOSTemplates,
AOT, RunOniOS) continue provisioning Xcode as they build or run
iOS/macOS targets

```yaml
- template: /eng/pipelines/arcade/setup-test-env.yml
  parameters:
    mauiSourcePath: ${{ parameters.mauiSourcePath }}
    buildConfig: ${{ parameters.buildConfig }}
    repoLogPath: ${{ parameters.repoLogPath }}
    # Skip Xcode provisioning for Android-only tests (RunOnAndroid category)
    # All other tests may build or run iOS/macOS targets and need Xcode
    skipXcode: ${{ eq(job.testCategory, 'RunOnAndroid') }}
```

Backward compatible - no behavior change for existing tests.

> [!WARNING]
>
> <details>
> <summary>Firewall rules blocked me from connecting to one or more
addresses (expand for details)</summary>
>
> #### I tried to connect to the following addresses, but was blocked by
firewall rules:
>
> - `https://api.github.com/graphql`
> - Triggering command: `/usr/bin/gh gh issue view 34049 --json
title,body,comments --jq {title: .title, body: .body, comments:
[.comments[] | {author: .author.login, body: .body}]}` (http block)
>
> If you need me to access, download, or install something from one of
these locations, you can either:
>
> - Configure [Actions setup
steps](https://gh.io/copilot/actions-setup-steps) to set up my
environment, which run before the firewall is enabled
> - Add the appropriate URLs or hosts to the custom allowlist in this
repository's [Copilot coding agent
settings](https://github.com/dotnet/maui/settings/copilot/coding_agent)
(admins only)
>
> </details>

<!-- START COPILOT CODING AGENT TIPS -->
---

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Author: rmarinho

eng/pipelines/arcade/setup-test-env.yml

@@ -5,6 +5,7 @@ parameters:
   installPackageArtifacts: true
   buildMSBuildTasks: false
   androidSdkRoot: $(ANDROID_SDK_ROOT)
+  skipXcode: false
 
 steps:
 - checkout: self
@@ -21,8 +22,8 @@ steps:
     skipAndroidEmulatorImages: true
     skipAndroidCreateAvds: true
     skipProvisioning: true
-    skipXcode: false
-    skipSimulatorSetup: false
+    skipXcode: ${{ parameters.skipXcode }}
+    skipSimulatorSetup: ${{ parameters.skipXcode }}
 
 - task: UseDotNet@2
   displayName: 'Use .NET SDK $(DOTNET_VERSION)'

eng/pipelines/arcade/stage-integration-tests.yml

@@ -33,6 +33,9 @@ stages:
           mauiSourcePath: ${{ parameters.mauiSourcePath }}
           buildConfig: ${{ parameters.buildConfig }}
           repoLogPath: ${{ parameters.repoLogPath }}
+          # Skip Xcode provisioning for Android-only tests (RunOnAndroid category)
+          # All other tests may build or run iOS/macOS targets and need Xcode
+          skipXcode: ${{ eq(job.testCategory, 'RunOnAndroid') }}
 
       - template: /eng/pipelines/common/run-dotnet-preview.yml
         parameters: