Make Helix-Service DeployQueues mockable

[chcosta]

https://dev.azure.com/dnceng/internal/_git/dotnet-helix-machines/pullRequest/42875#1728348479

DeployQueues isn't easily testable. QueueManager has some methods that should be testable (ie BuildScaleSetDeploymentTemplate), but because it wasn't designed with testing in mind, there's currently no unit tests. After https://dev.azure.com/dnceng/internal/_git/dotnet-helix-machines/pullrequest/43371 is merged, we will at least have a test project for deployqueues and then we can start implementing mockable classes to improve validation.

Release Note Category

• [ ] Feature changes/additions
• [ ] Bug fixes
• [x] Internal Infrastructure Improvements

Release Note Description