Remove intermediate images when using docker multi-stage builds

[mkurz]

Each time running the docker plugin with MultiStage as dockerPermissionStrategy (which is the default) an untagged image will be created (in addition to the final image). That is just how multi-stage works. However, this can escalate quickly and you get many many untagged images which (usually) no one ever needs. Therefore I propose to add a config (like autoCleanupIntermediateImages) which makes the plugin remove those images after docker:publish... has finished (we can even turn it on by default).
The solution is very easy, we just need to label the created intermediate image and then remove images with this label:
moby/moby#34513 (comment)

I propose to add two labels, one specific one for that image, so we can remove exactly that image on build cleanup and one general label, in case autocleanup is disabled, someone can later still remove all intermediate images generated by the docker plugin by just filtering for that general label.

[muuki88]

Thanks for this feature request. This duplicatse #1229