Fix and un-quarantine CanUseAntiforgeryAfterInitialRender test

[oroztocil]

Un-quarantines the ServerRenderingTests.FormHandlingTests.CanUseAntiforgeryAfterInitialRender test and attempts to fix its flakiness.

There seems to be a race condition due to which the result element can get re-rerendered between when we acquire a WebElement reference to it (using the Browser.Exists method) and when we read the element's text value. When that happens, StaleElementReferenceException is thrown. The PR tries to remove the flakiness by wrapping the access in a try/catch block in a Browser.True assertion, effectively adding a retry mechanism.

The test currently has no failures in the last 30 days on the quarantined test CI report. However, I have observe StaleElementReferenceException related failures when running the test locally in a loop (roughly 1 failure per 500 runs). With the PR change, the test has not failed in 3000 runs.

Fixes #57766

[Copilot]

Pull Request Overview

Fixes a flaky E2E test by addressing a race condition that caused StaleElementReferenceException when reading element text. The fix replaces a direct element access pattern with a retry mechanism to handle cases where the element gets re-rendered between acquiring the WebElement reference and reading its text value.

• Removes the [QuarantinedTest] attribute to re-enable the test
• Wraps element access in a try-catch block within a Browser.True assertion for automatic retries
• Addresses the StaleElementReferenceException race condition

[oroztocil]

@ilonatommy I combined the interactive rendering condition in the component with a simplified retrying assertion in the test itself. If I get 3k successful runs (my arbitrary benchmark), I would merge it like this.

[oroztocil]

/backport to release/10.0

[github-actions]

Started backporting to release/10.0: https://github.com/dotnet/aspnetcore/actions/runs/17649932628