Multi-stage docker build

[iamtroy412]

This PR is for a multi-stage docker build of the slurm test environment. This will allow us to remove the static RPMs from git and build them as new slurm versions are added to the test list. The first stage installs the required devel packages for all possible plugins then builds the slurm RPMs. The second stage copies in the slurm RPMs from the first stage and installs them.

• Removes version 20.02.5. As slurm versions are removed from the download archive, they should be dropped from testing
• Add version 22.05.11, the version currently running on the cluster
• Removed rpms from git
• Build and install the slurmrestd package by default

Tested locally using;
podman build -t slurm-test-env:22.05.11 -f Dockerfile --build-arg SLURM_VERSION=22.05.11
podman run -it --rm -v ./tests/:/tests localhost/slurm-test-env:22.05.11 bats /tests

[iamtroy412]

github actions files need to be updated, but wanted to get any feedback from testing locally first.

[djperrefort]

Changes to the docker file look good. Doesn't the entrypoint script need updating to launch the rest API daemon? I tried running the slurmrestd command from within the container but I get the following error:

slurmrestd: fatal: Unable to unshare System V namespace: Operation not permitted

[iamtroy412]

Yeah, the entrypoint script needs to be updated, as well as the slurm.conf files to enable the JWT auth to the slurmctld daemon. I'd like to address that in a different PR though, and keep this one just to the multi-stage build and building/installing the slurmrestd package. I'll reference #116 in a new PR that sets up and configures the rest daemon.

[djperrefort]

SGTM. Merge at will.