debug.fail fail when publishing a ClickOnce application using Debug MSBuild

### Steps to reproduce

Use a version of MSBuild built in debug mode. To make such a version:
1. Open an administrator command prompt
2. Switch to powershell by invoking powershell.exe
3. set-executionpolicy
- unrestricted
4. From the msbuild folder, run `.\script\Deploy-MSBuild.ps1 -configuration Debug -destination `

*Note* This overwrites some of your MSBuild binaries. To restore them, copy them from the newly created `Backup-` folder.

Then run these steps:
1. Create a project, such as WPF/Winforms project.
2. Right click on Reference open Manage NuGet Packages…
3. Click Settings and set the package management format to PackageReference .
4. Install a NuGet package such as Newtonsoft.Json.
5. Publish and install the project.
6. On Signing page uncheck the 'Sign the ClickOnce manifests'.
7. Publish the project.

### Expected behavior
It opens an explorer window from which you can run setup.exe. Doing so (and installing it) fails because of #4824.

### Actual behavior
Fails before it gets there with this error:

```
---------------------------
Assertion Failed: Abort=Quit, Retry=Debug, Ignore=Continue
---------------------------
Validation results have already been added for culture '{0}' en at Microsoft.Build.Tasks.Deployment.Bootstrapper.ProductValidationResults.AddPackageResults(String culture, XmlValidationResults results)
at Microsoft.Build.Tasks.Deployment.Bootstrapper.BootstrapperBuilder.ExploreDirectory(String strSubDirectory, XmlElement rootElement)
at Microsoft.Build.Tasks.Deployment.Bootstrapper.BootstrapperBuilder.RefreshProducts()
at Microsoft.Build.Tasks.Deployment.Bootstrapper.BootstrapperBuilder.Refresh()
at Microsoft.Build.Tasks.Deployment.Bootstrapper.BootstrapperBuilder.get_Products()
at Microsoft.VisualStudio.Publish.BaseProvider.BootstrapperManager.GetProducts()
at Microsoft.VisualStudio.Publish.ClickOnceProvider.BuildManager.GetBootstrapperProducts()
at Microsoft.VisualStudio.Publish.BaseProvider.BootstrapperProperties.LoadBootstrapperProducts()
at Microsoft.VisualStudio.Publish.BaseProvider.BootstrapperProperties.GetDefaultBootstrapperItems()
at Microsoft.VisualStudio.Publish.BaseProvider.BootstrapperProperties.Reset()
at Microsoft.VisualStudio.Publish.BaseProvider.BootstrapperProperties..ctor(ProductGetterDelegate ProductGetter, ProjectKind ProjectKind, PublishProvider PublishProvider)
at Microsoft.VisualStudio.Publish.ClickOnceProvider.PublishProperties..ctor(PublishProvider provider)
at Microsoft.VisualStudio.Publish.ClickOnceProvider.PublishProvider..ctor(IPublishManager PublishManager)
at Microsoft.VisualStudio.Publish.Framework.PublishFactory.CreateProvider(IPublishManager publishManager, String context)
at Microsoft.VisualStudio.Publish.Framework.PublishManager..ctor(Project project, IVsCfgProvider cfgProvider, String context)
at Microsoft.VisualStudio.Publish.Framework.PublishProject.SetObjects(Object obj, IVsCfgProvider cfgProvider, String Context)
---------------------------
Abort Retry Ignore
---------------------------
```

This appears when debug.fail is fallaciously called. This may be a signal that something else is wrong, or it's possible that the check is simply too aggressive.