e2e test pulling private bundle image from an image registry

[anik120]

#1322 added the ability to install ClusterExtensions with bundle images that are private. We should add e2e tests that test installing ClusterExtenstions with private bundle images.

We should not reach out to an external image registry to access a private image. Instead, we should use the existing internal image registry during our e2e tests to push a private image that can then be used for "private images" tests.