Refactor tests to work with or without local registry setup

[pendo324]

Right now, all of the tests are written to use the localImages map which is only populated if the SetupLocalRegistry function is first called.

The code should be refactored such that the tests don't care about such details and work regardless of whether the images are local or not (maybe through a helper struct with a GetImage(localImage) method).

See here for an example error.