Remove unused function

[oyvindeide]

Simplifies maintenance.

• 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 90.70%. Comparing base (9817d75) to head (dd1781d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9061   +/-   ##
=======================================
  Coverage   90.70%   90.70%           
=======================================
  Files         349      349           
  Lines       21776    21768    -8     
=======================================
- Hits        19751    19744    -7     
+ Misses       2025     2024    -1     

Flag	Coverage Δ
cli-tests	38.99% <0.00%> (+<0.01%)	⬆️
gui-tests	71.73% <0.00%> (+0.02%)	⬆️
performance-tests	49.28% <100.00%> (+0.03%)	⬆️
unit-tests	79.54% <100.00%> (+<0.01%)	⬆️

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[yngve-sk]

LGTM