Circuit not disconnect on all app exit scenarios

[captainsafia]

The Blazor Server client is configured to disconnect the circuit when the user navigates away from a page.

Previously, this disconnect happened on the browser's unload event, but this event isn't dispatched in all scenarios. it was changed to beforeunload but that was dispatched on too many scenarios.

We need to figure out a reliable event to listen to that strikes a balance between:

• Being dispatched reliably on all browsers
• Not being dispatched in false positive scenarios (e.g. triggering a download)

Previous issue description

The ClosingTheBrowserWindow_GracefullyDisconnects_WhenNavigatingAwayFromThePage test fails.

Ref: https://dev.azure.com/dnceng/public/_build/results?buildId=689837&view=ms.vss-test-web.build-test-results-tab

Output:

Assert.Contains() Failure\r\nNot found: (Debug, CircuitTerminatedGracefully)\r\nIn value: List<ValueTuple<LogLevel, String>> [(Debug, CircuitDisconnectStarted), (Debug, CircuitNotActive), (Information, ExecutedEndpoint), (Information, RequestFinished)]

   at Microsoft.AspNetCore.Components.E2ETest.ServerExecutionTests.CircuitGracefulTerminationTests.ClosingTheBrowserWindow_GracefullyDisconnects_WhenNavigatingAwayFromThePage() in /_/src/Components/test/E2ETest/ServerExecutionTests/CircuitGracefulTerminationTests.cs:line 87
--- End of stack trace from previous location ---

[mkArtakMSFT]

@captainsafia @javiercn thinks that you may have already fixed this. Should this be closed now?

[captainsafia]

@captainsafia Yes, this might be resolved by #23224. The best action to take on this would be to wait 20 days or so and unquarantine it if it is passing. If it's still failing (I highly doubt that will happen), we can look into a fix.

[captainsafia]

I updated this test to add a check to see if it timed out or ran successfully. This will help us nail down whether it is a legitimate failure or not. Keeping this issue open to see what this new check uncovers.