Rename according to feedback.

[ilonatommy]

Description

• Rename anchor to marker.
• This PR does not remove the exception flow from the enhanced nav supression utilities, as suggested in Run entire E2E test with consistent enhanced navigation suppression setting #63132 (comment). All the operations on browser/driver when the session is closed result in an "invalid session id" exception. At the same time, there is no property that would not trigger an exception and that we can check to define if the browser is still running. Even if we try an approach of finding the process with the browser to check its HasExited property, we are not able to find it without executing code on the webdriver - that will also throw the exception in question.

Follow up for #63132

[Copilot]

Pull Request Overview

This PR renames HTML element IDs from session-storage-anchor to session-storage-marker across multiple test files in response to feedback from a previous pull request. The change maintains consistency in naming conventions used for session storage testing utilities.

• Rename session-storage-anchor ID to session-storage-marker across test assets
• Update corresponding test utility code to reference the new ID
• Maintain existing enhanced navigation suppression exception handling

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/Index.razor	Update h1 element ID from session-storage-anchor to session-storage-marker
src/Components/test/testassets/BasicTestApp/Index.razor	Update p element ID from session-storage-anchor to session-storage-marker
src/Components/test/E2ETest/ServerRenderingTests/EnhancedNavigationTestUtil.cs	Update test utility to reference new session-storage-marker ID
src/Components/WebAssembly/testassets/StandaloneApp/Pages/Index.razor	Update h1 element ID from session-storage-anchor to session-storage-marker