[1.16] Add more image build jobs

[HadrienPatte]

Couple CI updates:

First, remove the build-docker-image- prefix from the images build jobs so we can actually see which job builds which image instead of that:

• Add build jobs for operator variants generic (gcp), aws and azure so we can start using those slimmer images in the appropriate environments
• duplicate the kvstoremesh image into clustermesh-apiserver so we can start renaming image references from the old name to the new one.
• misc gitlab-ci syntax improvements (using extends keywork instead of yaml anchors, using defaults).
• Add build jobs for a fips-based version of the operator and the aws operator

Example of the new pipeline after this PR: