Skip incremental build timing assertions for NativeAOT

[Copilot]

Summary

The RepetiviteBuildUpdateSingleResource(NativeAOT) test was failing because NativeAOT incremental builds aren't necessarily faster than clean builds. Incremental build timing is not a feature we care about for NativeAOT.

Changes

Guarded only the timing comparison assertions with if (runtime != AndroidRuntime.NativeAOT) in three tests, so the tests continue to run for NativeAOT and still validate incremental target-skipping behavior:

• RepetiviteBuildUpdateSingleResource (AndroidUpdateResourcesTest.cs) — the reported failing test; guarded the 1st-vs-2nd build time assertion
• BasicApplicationRepetitiveBuild (IncrementalBuildTest.cs) — guarded the 1st-vs-2nd build time assertion
• AppProjectTargetsDoNotBreak (IncrementalBuildTest.cs) — guarded the 3rd-vs-1st and 3rd-vs-2nd build time assertions

BasicApplicationRepetitiveReleaseBuild already skips non-MonoVM runtimes, so no change was needed there.

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[Copilot]

Pull request overview

This PR updates Xamarin.Android build/test coverage to stop asserting incremental-build timing improvements for the NativeAOT runtime, since NativeAOT incremental builds aren’t guaranteed to be faster than clean builds.

Changes:

• Skip BasicApplicationRepetitiveBuild for AndroidRuntime.NativeAOT via Assert.Ignore.
• Skip AppProjectTargetsDoNotBreak for AndroidRuntime.NativeAOT via Assert.Ignore.
• Skip RepetiviteBuildUpdateSingleResource for AndroidRuntime.NativeAOT via Assert.Ignore.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/IncrementalBuildTest.cs	Adds NativeAOT Assert.Ignore to two timing-sensitive incremental build tests.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/AndroidUpdateResourcesTest.cs	Adds NativeAOT Assert.Ignore to an incremental resource update test with a timing assertion.

[jonathanpeppers]

@copilot can you address the review comments: #10937 (review)

[Copilot]

@copilot can you address the review comments: #10937 (review)

Addressed in c30674b. Instead of skipping entire tests with Assert.Ignore, I now guard only the timing assertions with if (runtime != AndroidRuntime.NativeAOT) so all incremental target-skipping behavior is still validated for NativeAOT.