Migrate labs to new Knowledge Graph view

[monodot]

The workshop labs currently send users into Application Observability to explore their OpenTelemetry services. We need to update them to use the Entity Catalogue instead.

• Update the lab pages that reference App O11y
• Replace navigation steps & screenshots that point at App O11y, with the equivalent in Entity Catalogue or similar
• Update the workshop slide deck to match the new flow
• Verify the full lab flow end-to-end