[release/2.3] Merge from internal

[wtgodbe]

Should be merge-committed, not squashed

[dotnet-policy-service]

Hey @dotnet/aspnet-build, looks like this PR is something you want to take a look at.

[Copilot]

Pull Request Overview

This PR merges changes from the internal release/2.3 branch with updates focused on sign-in behavior and test coverage for the sign-in workflow.

• Updated the resignation flows to rely on an explicit parameter list without suppressing warnings.
• Added two new tests to verify proper error logging and no-op behavior in RefreshSignInAsync when sign-in conditions are not met.
• Revised RefreshSignInAsync in the core to handle unauthenticated and mismatched user cases with early returns after error logging.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/Identity/test/Identity.Test/SignInManagerTest.cs	Updated test methods for resigning sign in, including improved ClaimsIdentity usage and additional tests for error cases.
src/Identity/Core/src/SignInManager.cs	Modified RefreshSignInAsync to log errors and exit early if sign-in preconditions are not satisfied.

Comments suppressed due to low confidence (2)

src/Identity/test/Identity.Test/SignInManagerTest.cs:558

• [nitpick] Consider replacing the hard-coded 'authscheme' string with a constant or configuration value to improve consistency and reduce duplication.

var id = new ClaimsIdentity("authscheme");

src/Identity/test/Identity.Test/SignInManagerTest.cs:634

• [nitpick] The literal 'different' is used to simulate a mismatched user ID; consider using a more descriptive constant or variable name for clarity.

manager.Setup(m => m.GetUserId(claimsPrincipal)).Returns("different");