Different builders with the same tag will cause a reconciliation loop

[tylerphelan]

If multiple different Builders or Clusterbuilders are configured with the same tag, kpack will think that the digest has changed and will continuously rebuild and rewrite the builder images to its configured tag causing endless reconciliation loops and registry pressure.

This issue has shown up when users install kpack to different clusters but use the same kp default repository and the same cb names which results in duplicate tags across the clusters. This isn't obvious to diagnose.

This may just be something to document.

[matthewmcnew]

Adding the "needs discussion" label to this issue. It is unclear to me if we want to modify this behavior. kpack is correctly updating the image on the registry to match the desired configuration in the Builder resource.