Fix test for missing response

[dafeda]

Issue
Resolves #4990

Pre review checklist

• Added appropriate release note label
• PR title captures the intent of the changes, and is fitting for release notes.
• Commit history is consistent and clean, in line with the contribution guidelines.
• Updated documentation
• Ensured new behaviour is tested

Adding labels helps the maintainers when writing release notes. This is the list of release note labels.

[codecov-commenter]

Codecov Report

Merging #5274 (3af200a) into main (e219980) will increase coverage by 11.99%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##             main    #5274       +/-   ##
===========================================
+ Coverage   73.21%   85.21%   +11.99%     
===========================================
  Files         391      338       -53     
  Lines       26938    20205     -6733     
  Branches     1965        0     -1965     
===========================================
- Hits        19724    17217     -2507     
+ Misses       6650     2988     -3662     
+ Partials      564        0      -564     

Impacted Files	Coverage Δ
src/ert/analysis/_es_update.py	86.07% <100.00%> (+0.15%)	⬆️
src/ert/storage/local_ensemble.py	95.28% <100.00%> (+0.01%)	⬆️

... and 54 files with indirect coverage changes

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[oyvindeide]

LGTM!