Fix: Error during templating due to inconsistent elements order in array

[pcortada-te]

Description

I was getting

Traceback (most recent call last):
...
  File "/home/atlantis/.atlantis/repos/thousandeyes/thousandeyes-aws-infrastructure/22840/default/stacks/eks-resources/layers/stg-fra1_eks1/.venv/lib/python3.13/site-packages/stacks/filters/lookup.py", line 40, in terraform_init_headless
    helpers.json_write({"terraform": [{"backend": code["terraform"][0]["backend"]}]}, remote_ctx.universe_file)
                                                  ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
KeyError: 'backend' code["terraform"] 

as `code[“terraform”]`` has 2 elements and backend is in the 2nd one [1], not the first [0]. I assume a change in python-hcl2 lib may have caused a change in the output(?)

The fix is a quick search for the correct block, I focused in readibility, it can be more pythonic but it gets confusing.

Type of Change

• Bug Fix
• New Feature
• Breaking Change
• Refactor
• Documentation
• Other (please describe)

Checklist

• I have read the contributing guidelines
• Existing issues have been referenced (where applicable)
• I have verified this change is not present in other open pull requests
• [N/A ] Functionality is documented
• All code style checks pass
• New code contribution is covered by automated tests
• All new and existing tests pass