Revamp container images to be smaller/more efficient

Currently, the OCI container images deployed within the Skampi environment are growing and are suspected of bloat (approx. 1GB and greater in some instances).

The build and deployment process could benefit from the image build processes being revisited in order to trim the image size and improve the build efficiency.  The flow on effect of this will be an improve in image build time, and faster deployments.

• Upstream base images for Skampi deployments are evaluated for quality and trim, with optimal selected.  Consistency across projects is applied to maximise layer reuse.
• Skampi related Dockerfiles are reorganised and streamlined to take advantage of best practices for build performance and size.

The images deployed on Skampi are now improved on both size and building speed although a major improvement in this regard will need a different and substantially more cumbersome approach.

With the present technology using Dockerfile and Ubuntu/Debian images (and Alpine were possible) the System Team undertook a series of actions:

• Slightly improve the building speed for the tango images (we realized it was mostly optimized already although an effort was taken in improving its readability).
• Document image building best practices: https://developer.skao.int/en/latest/tools/containers/container-cheat-sheet.html
• Use alpine Linux to build a new set of tango images `tango-*-alpine` (those now exist as a parallel to existing images and a strategy must be defined for substituting them in the pipelines and relevant charts while retiring the existing ones).