[enhancemnet] Separate release image and test image

[gaocegege]

Now we build one image for release and e2e test, I think we should keep the release image clean and small.

More detail: #374 (comment)

That's a good point. I think when our release infra is more mature and its easier to build multiple images that will make sense.

Practically speaking the sample added in this PR takes up no space. The biggest space is probably nodejs for the UI vs. operator.

Actually, I am thinking if we should separate the UI and the operator. Maybe we should place the UI in an independent repo.

[stale]

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