Fix not unsubscribing in trace detail on navigation

[JamesNK]

Description

The trace detail page isn't unsubscribing from repository updates when navigating away. That causes a memory leak by holding onto the TraceDetail page instance from the singleton TelemetryRepository instance.

Changes:

• TraceDetail didn't implement dispose. That means navigating away from the page never cleaned up subscriptions.
• UpdateDetailViewData created a subscription, but the subscription callback also called UpdateDetailViewData. In the right circumstances two subscriptions are created but only one is disposed.
• Added TraceDetail page tests

Profiler showing data leak when repeatedly navigating to and from trace details page:

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Is this introducing a breaking change?
      • Yes
        • Link to aspire-docs issue (please use this breaking-change template):
      • No
        • Link to aspire-docs issue (please use this doc-idea template):
  • No

Microsoft Reviewers: Open in CodeFlow