Auth metrics updates

[JamesNK]

• Change user.is_authenticated to aspnetcore.user.is_authenticated. Feedback at Add ASP.NET Core AuthN and AuthZ metrics open-telemetry/semantic-conventions#2531 (comment) is there isn't a standard on attributes for user.* so we shouldn't use it. It could be aspnetcore.user.is_authenticated or aspnetcore.identity.is_authenticated
• Change metric units to not all be {request}.
  • Authorization API isn't tied to HTTP requests so it doesn't make sense there.
  • While the authentication API does take HttpContext as an argument, so involves requests, I think there are better units.

[Copilot]

Pull Request Overview

This PR updates authentication and authorization metrics to improve naming conventions and accuracy. The changes align with OpenTelemetry semantic conventions by using namespaced attributes and more precise metric units.

• Change metric attribute from user.is_authenticated to aspnetcore.user.is_authenticated to follow OpenTelemetry semantic conventions
• Rename metric units from generic {request} to more specific units like {attempt}, {challenge}, {forbid}, {sign_in}, and {sign_out}
• Update method names to better reflect the actual operations being measured

Reviewed Changes

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

File	Description
src/Security/Authorization/Core/src/DefaultAuthorizationServiceImpl.cs	Updates method calls from AuthorizedRequestCompleted to AuthorizeAttemptCompleted
src/Security/Authorization/Core/src/AuthorizationMetrics.cs	Renames metrics infrastructure with more accurate terminology and updates attribute naming
src/Http/Authentication.Core/src/AuthenticationMetrics.cs	Updates metric units to be more specific to the actual operations being measured

[MackinnonBuck]

Thanks!