client: rmi deletes all tags for image id

[dweomer]

Logically this makes sense but it will surprise people. Either document the deviation or fix it to work like docker rmi.

[ibuildthecloud]

This is not the intended behavior. I think it's a side effect of how containerd-cri works. We should figure out what needs to change to do the proper thing. Possibly just go directly to containerd or see if we can get the behavior of containerd-cri to change. It seems like it might be wrong.