Splitting up CI matrix for pip llnl

[MishaZakharchanka]

This PR focuses on the pip CI for LLNL machines. The functionality of the tests remains the same, but the jobs will now be listed individually on gitlab. Additionally, there was organizational work done in an attempt to make the file more readable and maintainable.

[MishaZakharchanka]

Do we want to add Lassen back to the machines that we are testing on?

[mtitov]

Do we want to add Lassen back to the machines that we are testing on?

Yes.

And can you please investigate having a list of tags for $RUNNER_TYPE, since we need to add tag slurm for Slurm batch-runners (e.g., RUNNER_TYPE: [ "batch", "slurm" ]?)

[MishaZakharchanka]

And can you please investigate having a list of tags for $RUNNER_TYPE, since we need to add tag slurm for Slurm batch-runners (e.g., RUNNER_TYPE: [ "batch", "slurm" ]?)

Its looks like variables are only allowed to be strings, so I would write a comment to change 'batch' to 'slurm' either 6/1 or when the machines change schedulers to flux.