Fix DependencyProperty test

[ThomasGoulet73]

Description

Fixes the test failure seen in main currently. This was caused by the switch from xUnit test runner to VSTest test runner introduced in #10514 which changed the order in which test were ran and exposed an existing bug in the tests.

The problem is because the xUnit test runner ran the test Register_InvokeStringTypeTypeValidateFail_Throws before Register_InvokeStringTypeType_Success and VSTest test runner runs them in inverse order. This causes problem because both test registers a dependency property for the same type with the same property name, the thing is that Register_InvokeStringTypeTypeValidateFail_Throws expects the registration to fail and not register the dependency property in the cache while Register_InvokeStringTypeType_Success expects the registration to succeed and register the dependency property in the cache.

When the order is Register_InvokeStringTypeTypeValidateFail_Throws -> Register_InvokeStringTypeType_Success it's fine because the dependency property is not in the cache for the second test.
When the order is Register_InvokeStringTypeType_Success -> Register_InvokeStringTypeTypeValidateFail_Throws it fails because Register_InvokeStringTypeTypeValidateFail_Throws fails early because the property is already registered for the second test.

Here's the 2 conflicting dependency property name + type:

wpf/src/Microsoft.DotNet.Wpf/tests/UnitTests/WindowsBase.Tests/System/Windows/DependencyPropertyTests.cs

Line 19 in 009ae5a

yield return new object?[] { " ", typeof(int), typeof(DependencyObjectTests), 0 };

wpf/src/Microsoft.DotNet.Wpf/tests/UnitTests/WindowsBase.Tests/System/Windows/DependencyPropertyTests.cs

Lines 299 to 300 in 009ae5a

	yield return new object?[] { " ", typeof(int), typeof(DependencyObjectTests), null, 0 };
	yield return new object?[] { " ", typeof(int), typeof(DependencyObject), new PropertyMetadata(), 0 };

Side note:
We should probably refactor how tests are done for DependencyProperty, this PR is just a patch to fix the current failure. IMO we should have 1 type per tests that register dependency properties, if we don't want to have a mess of types we could possibly create the types at runtime using IL emit.

Customer Impact

None, tests only.

Regression

WPF tests regression only.

Testing

Running the tests locally.

Risk

Low to none, tests only.

Microsoft Reviewers: Open in CodeFlow

[ThomasGoulet73]

@dotnet/wpf-developers: It would be a good idea to prioritize this to fix the test failures in main and unblock other PRs.

[dipeshmsft]

LGTM

[codecov]

Codecov Report

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Additional details and impacted files

@@            Coverage Diff             @@
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  Partials        ?         993           

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[singhashish-wpf]

Thank you @ThomasGoulet73 ! 🙏

[h3xds1nz]

@ThomasGoulet73 #10323 looks like you got to it sooner haha