Dockerfile.test: build critools in a separate stage
Dockerfile.test: build critools in a separate stage

Building critools only requires the install script and the critools-version
file (to determin the version to build). Moving it to a separate stage
prevents rebuilding it if unrelated changes are made in the code.

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

containerd/containerd,mikebrow/containerd,thaJeztah/containerd,estesp/containerd,estesp/containerd,thaJeztah/containerd,dmcgowan/containerd,dmcgowan/containerd,mikebrow/containerd,containerd/containerd