Exercise ExecWithRetries MSBuild task in Arcade Validation

[missymessa]

ExecWithRetries was modified during the Post Build Signing feature. It's functionality should be exercised using Arcade Validation.

Related PRs:

• Create modified msi package drop #5442

Code that needs testing:

• https://github.com/dotnet/arcade/blob/master/src/Microsoft.DotNet.Build.Tasks.SharedFramework.Sdk/targets/windows/wix.targets

[missymessa]

Putting this back in the backlog as it's not as high of a priority to test for this epic.