`aspire ps` hangs if app host has no url or on breakpoint

Nobody has claimed this yet.

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Describe the bug

If you have an app host that's broken on a breakpoint, the `aspire ps` command gets stuck on `Scanning for running apphosts...`. (At least it got stuck for over a minute before I got bored and gave up)

### Expected Behavior

`aspire ps` shouldn't hang indefinitely.

### Steps To Reproduce

1. Use the below code
2. Set a breakpoint on the last line
3. Start the app host with debugger
4. Once your breakpoint is hit, run `aspire ps`
```
#:package Aspire.Hosting.Azure.CosmosDB@13.3.0-pr.15503.g3532eede
#:sdk Aspire.AppHost.Sdk@13.3.0-pr.15503.g3532eede

#pragma warning disable ASPIRECOSMOSDB001 // Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.

var builder = DistributedApplication.CreateBuilder(args);

builder.AddAzureCosmosDB("cosmos")
.RunAsPreviewEmulator(x => x.WithDataExplorer());

using var app = builder.Build();

await app.StartAsync();

// SET BREAKPOINT HERE
await Task.Delay(Timeout.Infinite);
```

### Exceptions (if any)

_No response_

### .NET Version info

_No response_

### Anything else?

_No response_

Start by reproducing the issue with the provided app-host code, a breakpoint on the final line, and the `aspire ps` command. Trace the `Scanning for running apphosts...` path and verify that `aspire ps` completes with a useful result instead of hanging indefinitely when the app host has no URL or is paused at a breakpoint.

Written by the indexing model from the issue text.