Try fix env pollution

[larsevj]

Should resolve failing tests such as
https://github.com/equinor/ert/actions/runs/26239888641/job/77223404795?pr=13617
https://github.com/equinor/ert/actions/runs/26439598491/job/77830775009?pr=13629

• PR title captures the intent of the changes, and is fitting for release notes.
• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.
• Make sure unit tests pass locally after every commit (git rebase -i main --exec 'just rapid-tests')

When applicable

• When there are user facing changes: Updated documentation
• New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• Large PR: Prepare changes in small commits for more convenient review
• Bug fix: Add regression test for the bug
• Bug fix: Add backport label to latest release (format: 'backport release-branch-name')

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.49%. Comparing base (15477f3) to head (1c3cdf9).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13624      +/-   ##
==========================================
- Coverage   89.54%   89.49%   -0.05%     
==========================================
  Files         464      464              
  Lines       32779    32779              
==========================================
- Hits        29353    29337      -16     
- Misses       3426     3442      +16     

Flag	Coverage Δ
cli-tests	35.76% <ø> (ø)
fuzz	43.95% <ø> (ø)
gui-tests	59.81% <ø> (-0.01%)	⬇️
performance-and-unit-tests	77.97% <ø> (-0.11%)	⬇️
test	45.40% <ø> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 3 files with indirect coverage changes