WinUI 3 tests failing at random in CI

### Describe the bug

The WinUI 3 tests that are run in the CI for build validation are sometimes failing with the following error:
```
Passed RequestsAsync (20,5) [4 ms]
Passed RequestsAsync (5,5) [< 1 ms]
Passed RequestsAsync (20,5,2500,1000,1000,1000,1000) [6 s]
The active test run was aborted. Reason: Unable to communicate with test host process.
Terminating app with process ID '14816'.
Results File: C:\a\Windows\Windows\TestResults\WinAppSdk.trx

The active Test Run was aborted because the host process exited unexpectedly. Please inspect the call stack above, if available, to get more information about where the exception originated from.
The test running when the crash occurred:
StackedNotificationsBehaviorExperiment.Tests.StackedNotificationsBehaviorTestClass.NotificationBehaviorSingleTest_StackedNotificationsBehaviorTestClass_Test

This test may, or may not be the source of the crash.
```

This seems to be happening more or less at random and can sometimes be resolved with a rerun. However, this has been happening more often in the last few weeks and is increasingly becoming a blocker for other work.

### Steps to reproduce

```text
Exact repro steps are unknown. Seems to only be happening in the CI and hasn't been reproduced locally.
```

### Expected behavior

Consistent test results, no failure if there's no problem.

### Screenshots

_No response_

### Code Platform

- [ ] UWP
- [ ] WinAppSDK / WinUI 3
- [ ] Web Assembly (WASM)
- [ ] Android
- [ ] iOS
- [ ] MacOS
- [ ] Linux / GTK

### Windows Build Number

- [ ] Windows 10 1809 (Build 17763)
- [ ] Windows 10 1903 (Build 18362)
- [ ] Windows 10 1909 (Build 18363)
- [ ] Windows 10 2004 (Build 19041)
- [ ] Windows 10 20H2 (Build 19042)
- [ ] Windows 10 21H1 (Build 19043)
- [ ] Windows 10 21H2 (Build 19044)
- [ ] Windows 10 22H2 (Build 19045)
- [ ] Windows 11 21H2 (Build 22000)
- [ ] Other (specify)

### Other Windows Build number

_No response_

### App minimum and target SDK version

- [ ] Windows 10, version 1809 (Build 17763)
- [ ] Windows 10, version 1903 (Build 18362)
- [ ] Windows 10, version 1909 (Build 18363)
- [ ] Windows 10, version 2004 (Build 19041)
- [ ] Windows 10, version 2104 (Build 20348)
- [ ] Windows 11, version 22H2 (Build 22000)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

_No response_

### Visual Studio Build Number

_No response_

### Device form factor

_No response_

### Additional context

_No response_

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