Metric for connected circuits drops to zero when a client disconnects

[danroth27]

When I look at the aspnetcore.components.circuit.connected metric for a default Blazor Web App in the .NET Aspire dashboard, the count initially reflects the number of connected clients but then drops to zero when a client disconnects and stays at zero even if more connected circuits are created.

Repro steps:

• Install .NET SDK 10.0.100-preview.5.25277.114
• Create a default Blazor Web app
• Retarget the app to net9.0 and add .NET Aspire orchestration
• Target the app back to net10.0
• Add the Microsoft.AspNetCore.Components.Server.Circuits meter in Extensions.cs
• Run the app and view the traces in the Aspire dashboard
• In the app browse to the Counter page in two separate tabs
• The number of active and connected circuits should show as 2
• Close one of the tabs

Expected result: The number of connected circuits drops to 1
Actual result: The number of connected circuits drops to zero and stays at zero even if you open additional tabs to create more connected circuits.