fix: Remove duplicate RadioButton sample page causing route conflict

The PR added Components/Pages/ControlSamples/RadioButton/Index.razor but
Pages/ControlSamples/RadioButton/Index.razor already existed with the same
@page route. The ambiguous route crashed the Blazor circuit, cascading
failures to 32 integration tests.

All 243 integration tests now pass.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: csharpfritz