Make server interface more explicit

[oyvindeide]

Related to: #8905

• 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 90.73%. Comparing base (5c7768f) to head (d3c2dc3).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9112      +/-   ##
==========================================
+ Coverage   90.69%   90.73%   +0.04%     
==========================================
  Files         350      350              
  Lines       21778    21778              
==========================================
+ Hits        19751    19760       +9     
+ Misses       2027     2018       -9     

Flag	Coverage Δ
cli-tests	39.02% <ø> (+0.04%)	⬆️
gui-tests	71.68% <ø> (ø)
performance-tests	49.24% <ø> (ø)
unit-tests	79.59% <ø> (-0.01%)	⬇️

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.