fix: container diff improvements
Closes #17 (closed)
Related to https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/team/-/issues/5513
The container-diff tool is deprecated/archived. https://github.com/GoogleContainerTools/container-diff
This removes it from the common-ci-tasks toolchain, switching to docker
to calculate the size of the before and after images.
It also adds a test for this include, and updates the documentation accordingly.
Edited by Andrew Newdigate