Ensure pre_experiment validation has access to plugin configuration

[berland]

This is a fixup of a regression in 1ae12f6

The bug slipped through as the feature is skipped unless the test is run on-premise

Issue
Resolves #9702

Approach
+

• 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

[codspeed-hq]

CodSpeed Performance Report

Merging #9703 will not alter performance

_{Comparing berland:fix_plugin_validation (cf618e8) with main (7b2bedf)}

Summary

✅ 24 untouched benchmarks

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.75%. Comparing base (7b2bedf) to head (cf618e8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9703      +/-   ##
==========================================
+ Coverage   91.73%   91.75%   +0.02%     
==========================================
  Files         426      426              
  Lines       26535    26535              
==========================================
+ Hits        24342    24348       +6     
+ Misses       2193     2187       -6     

Flag	Coverage Δ
cli-tests	39.81% <ø> (-0.01%)	⬇️
everest-models-test	34.16% <ø> (ø)
gui-tests	74.37% <ø> (+0.03%)	⬆️
integration-test	37.99% <ø> (ø)
performance-tests	51.59% <ø> (ø)
test	39.52% <ø> (ø)
unit-tests	74.23% <ø> (ø)

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