Avoid using deprecated --target-case in tests

[berland]

Issue
Deprecation warning from Ert

Approach
Do as Ert suggests.

• 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 'pytest tests/ert/unit_tests -n logical -m "not integration_test"')

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: Create Backport PR to latest release

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.73%. Comparing base (855c517) to head (e9c5eca).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9632   +/-   ##
=======================================
  Coverage   91.73%   91.73%           
=======================================
  Files         430      430           
  Lines       26639    26639           
=======================================
  Hits        24437    24437           
  Misses       2202     2202           

Flag	Coverage Δ
cli-tests	39.46% <ø> (ø)
everest-models-test	34.19% <ø> (ø)
gui-tests	71.83% <ø> (ø)
integration-test	38.29% <ø> (ø)
performance-tests	51.68% <ø> (ø)
test	39.61% <ø> (ø)
unit-tests	74.00% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[codspeed-hq]

CodSpeed Performance Report

Merging #9632 will not alter performance

_{Comparing berland:avoid_target_case (e9c5eca) with main (855c517)}

Summary

✅ 24 untouched benchmarks

[andreas-el]

🎯