Remove pydantic setting use_enum_values=True

[berland]

Reverting back to pydantic default behaviour. This implies at least that the queue_system member of QueueConfig is always of type QueueSystem, and never just a str, which breaks what the type hints say.

Issue
Related to #12462

Approach
Modify ruamel instead.

• 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')

[berland]

Does not fly as Everest is using ruamel which doesn't like StrEnum. Fixed

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.58%. Comparing base (4fb794e) to head (c31a1a0).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12464      +/-   ##
==========================================
- Coverage   90.60%   90.58%   -0.02%     
==========================================
  Files         433      433              
  Lines       29486    29492       +6     
==========================================
  Hits        26716    26716              
- Misses       2770     2776       +6     

Flag	Coverage Δ
cli-tests	37.62% <ø> (ø)
gui-tests	69.04% <ø> (-0.03%)	⬇️
performance-and-unit-tests	74.18% <50.00%> (-0.01%)	⬇️
test	38.48% <100.00%> (+0.01%)	⬆️

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[Copilot]

Pull request overview

This PR removes the pydantic use_enum_values=True configuration setting, reverting to pydantic's default behavior where enum fields are represented as enum instances rather than their string values. This change ensures that type hints accurately reflect runtime behavior, particularly for the QueueConfig.queue_system field which should be a QueueSystem enum instance, not a string.

Key Changes:

• Removed use_enum_values=True from QueueOptions base model configuration
• Added StrEnum representer to handle YAML serialization of enum instances in Everest config dumping

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/ert/config/queue_config.py	Removes use_enum_values=True from QueueOptions model config, ensuring enum fields remain as enum instances
src/everest/config/everest_config.py	Adds StrEnum representer for YAML serialization and necessary imports to properly serialize enum instances when dumping config to YAML

[codspeed-hq]

CodSpeed Performance Report

Merging #12464 will not alter performance

_{Comparing berland:no_use_enum_values (c31a1a0) with main (4fb794e)}

Summary

✅ 22 untouched

[berland]

Todo: Check all yaml.dump in the Everest codebase and make it into a common function.

[andreas-el]

Todo: Check all yaml.dump in the Everest codebase and make it into a common function.

Will this be verification for this PR, or a separate issue?

[andreas-el]

👌

[berland]

Todo: Check all yaml.dump in the Everest codebase and make it into a common function.

Will this be verification for this PR, or a separate issue?

This has now been fixed in this PR.