Simplify retry extension logic to use built-in filters

[Evangelink]

Fixes #7500

[Copilot]

Pull request overview

This PR simplifies the Retry extension by removing the custom test execution filter factory and instead relying on the platform’s built-in --filter-uid functionality when re-running failed tests.

Changes:

• Update RetryOrchestrator to remove any existing test filter options and apply --filter-uid with the failed test UIDs on retry.
• Remove the Retry extension’s custom ITestExecutionFilterFactory integration (and the default TestHostManager requirement).
• Add/adjust acceptance coverage to validate retry behavior when an initial filter is present.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/RetryFailedTestsTests.cs	Adds new acceptance scenarios for retry behavior with pre-existing filters and updates the embedded test asset to respect UID filtering.
src/Platform/Microsoft.Testing.Extensions.Retry/RetryOrchestrator.cs	Replaces the previous in-process filter approach by rewriting command line filters on retry and introduces helper logic to remove existing options.
src/Platform/Microsoft.Testing.Extensions.Retry/RetryExtensions.cs	Removes registration of the custom retry execution filter factory and the dependency on the default TestHostManager.
src/Platform/Microsoft.Testing.Extensions.Retry/RetryExecutionFilterFactory.cs	Deletes the custom filter factory implementation (no longer needed with built-in filtering).

[Copilot]

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 5 comments.