CTM-554 Fix terra_base vs. terra-base

[aednichols]

Fix a small issue introduced in #4888

terra-base is the image name while terra_base is the bash variable name, now they are properly separated.

This PR's only objective is to return the job to green status. Future PR(s) will address the 60 => 365 day expiration change.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.07%. Comparing base (4b932e4) to head (b035227).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #4915   +/-   ##
========================================
  Coverage    74.07%   74.07%           
========================================
  Files          131      131           
  Lines        11101    11101           
  Branches       891      891           
========================================
  Hits          8223     8223           
  Misses        2878     2878           

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[aednichols]

Regeneration confirmed fixed [0][1], marking ready for review.

[0] https://github.com/DataBiosphere/leonardo/actions/runs/27972142964
[1] https://console.cloud.google.com/compute/imagesDetail/projects/broad-dsp-gcr-public/global/images/leo-dataproc-image-2-2-52-debian12-2026-06-22-17-40-49?project=broad-dsp-gcr-public

[LizBaldo]

😬