[GoReleaser] Update docker to v2 syntax

[mowies]

GoReleaser introduced v2 of their docker image and manifest setup that combined images and manifests into one smarter builder.
We should see if we can easily introduce it and provide feedback where applicable.

[mowies]

I'm putting this on hold for now. There's still a lot of rough edges around the new implementation and we have a rather advanced setup which is not fully supported yet I think. The draft PR has a test config for collector core which has all options from before, but behaviour is different with the new setup and we can't fully switch for now.