Use image overrides when deploying

[mkolesnik]

Right now Shipyard uses a simplistic approach, setting repository and version when deploying to localhost:5000 and local respectively.
This necessitates that images be pre-loaded to the kind setup, even when testing projects that dont touch them (e.g. lighthouse).

Instead, we should use the image overrides feature to specify specific images to override, and let the rest be taken from the default repository.

As we have a PRELOAD_IMAGES variable that denotes which images we're preloading, using it would be classic for populating the overrides.

This also allows consuming projects to still preload a specific image if necessary (i.e. for testing changes locally), e.g. on subctl one could use make e2e PRELOAD_IMAGES=submariner-operator.

We should also add a test for deploying that the preloaded images are actually used (perhaps find if a pod uses a preloaded image, and if none found error out).