Unstable unit test: System.Windows.Forms.Tests.MenuStripTests.MenuStrip_WndProc_InvokeMouseActivateWithHandle_Success

Related #11227

### Test

System.Windows.Forms.Tests.MenuStripTests.MenuStrip_WndProc_InvokeMouseActivateWithHandle_Success

### Issue description

The case failed in [PR build](https://dev.azure.com/dnceng-public/public/_build/results?buildId=712165&view=ms.vss-test-web.build-test-results-tab&runId=17804108&resultId=111829&paneView=debug), the failed scenario:

- MenuStrip_WndProc_InvokeMouseActivateWithHandle_Success

**Error Message:**

- **In X64 unit:**

- Assert.Equal() Failure: Values differ
Expected: 0
Actual: 2

**Stack trace:**
```
at System.Windows.Forms.Tests.MenuStripTests.MenuStrip_WndProc_InvokeMouseActivateWithHandle_Success() in /_/src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/MenuStripTests.cs:line 777
at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
```