Revert "Merge branch '438865-add-container_registry[...]' into 'master'"

What does this MR do and why?

Revert "Merge branch '438865-add-container_registry_size-to-rest-api' into 'master'"

This reverts merge request !142362 (merged)

We need to revert this MR because it will result in duplicated (or at least, inaccurate) container registry sizes being stored.

This is because we add this value to the one fetched from the container registry API in the merged_attributes method.

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