CI: all programs cache saved even when exists

[JulianGCalderon]

When the all programs cache exists, it still tries to generate it, which causes the workflow to fail.

Failed to save: Unable to reserve cache with key all-programs-cache-..., another job may be creating this cache.
Warning: Cache save failed.

We should add a check to only try to generate it when it doesn't exist.

link: https://github.com/lambdaclass/cairo-vm/actions/runs/14316883762/job/40125097947#annotation:9:1364