MSTest attributes should be sealed in most cases.

[Youssef1313]

There is no point in inheriting many of the MSTest attributes and they should be made sealed.

• DiscoverInternalsAttribute
• DoNotParallelizeAttribute
• ParallelizeAttribute
• TestDataSourceDiscoveryAttribute
• WinUITestTargetAttribute
• STATestClassAttribute
• DataRowAttribute
• DataTestMethodAttribute (attribute should be removed altogether)
• UITestMethodAttribute (maybe?)