Investigate if buildx version can be removed

[Olha Yevtushenko]

buildx version in docker/setup-buildx-action GA was pinned for a year since this commit:
d000520

The reason: Docker manifests being broken for some k8s setups. This issue was raised in setup-buildx-action as well:
docker/setup-buildx-action#187

It appears that it is not solvable at the level of the GA but there are two workarounds:

• via pinned version as we use now
• via provenance flag

It makes sense to try out provenance flag and see if it can be used instead of pinned version.