Remove protobuf

[dafeda]

Pre review checklist

• Read through the code changes carefully after finishing work
• Make sure tests pass locally (after every commit!)
• Prepare changes in small commits for more convenient review (optional)
• PR title captures the intent of the changes, and is fitting for release notes.
• Updated documentation
• Ensured that unit tests are added for all new behavior (See
  Ground Rules),
  and changes to existing code have good test coverage.

Pre merge checklist

• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.

[codecov-commenter]

Codecov Report

Merging #6172 (1dc2df5) into main (3ecb021) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #6172      +/-   ##
==========================================
- Coverage   82.72%   82.66%   -0.06%     
==========================================
  Files         351      347       -4     
  Lines       21544    21245     -299     
  Branches      834      834              
==========================================
- Hits        17822    17562     -260     
+ Misses       3424     3385      -39     
  Partials      298      298              

Files	Coverage Δ
src/ert/__main__.py	81.85% <ø> (+0.24%)	⬆️
src/ert/cli/main.py	92.53% <100.00%> (-1.06%)	⬇️
src/ert/ensemble_evaluator/_builder/_ensemble.py	92.07% <ø> (+1.08%)	⬆️
src/ert/ensemble_evaluator/_builder/_legacy.py	92.78% <100.00%> (+0.78%)	⬆️
src/ert/job_queue/queue.py	90.41% <ø> (+2.28%)	⬆️
src/ert/run_models/base_run_model.py	94.00% <ø> (+<0.01%)	⬆️
src/ert/run_models/ensemble_experiment.py	97.61% <100.00%> (+6.47%)	⬆️
src/ert/shared/feature_toggling.py	89.74% <ø> (-10.26%)	⬇️

... and 1 file with indirect coverage changes

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[eivindjahren]

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