[CI] Cache test_data for translate tests

[romanc]

Description

Currently, translate tests go and fetch test_data/ from scratch every run. We had issues with data fetching in the past so I put in a cache under the assumption that GH cache servers are very reliable. They are also closer (in a network sense) to the executing machines, leading to slightly faster transfer times (not that this would matter in the 30min runtime that we are looking at).

How Has This Been Tested?

• Changed CI workflow is still passing.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation: N/A
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules: N/A
• New check tests, if applicable, are included
• Targeted model if this changed was triggered by a model need/shortcoming: N/A

[romanc]

@FlorianDeconinck Another quick PR to tie up loose ends before we start the new dev cycle.

I might put in something similar in the DaCe workflow once we re-enable these tests on DaCe's mainline branch. For now, I think we don't run enough DaCe tests that this would be justified.

[FlorianDeconinck]

LGTM. Hold for NOAA review