Simplifies run models by removing statefullness and replacing with arguments

[oyvindeide]

Issue
Removes some statefulness from the run models

Approach
Short description of the approach

(Screenshot of new behavior in GUI if applicable)

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 #6398 (6ee9a9c) into main (1b858eb) will decrease coverage by 0.03%.
The diff coverage is 91.30%.

@@            Coverage Diff             @@
##             main    #6398      +/-   ##
==========================================
- Coverage   83.35%   83.33%   -0.03%     
==========================================
  Files         343      343              
  Lines       20863    20857       -6     
  Branches      911      911              
==========================================
- Hits        17391    17381      -10     
- Misses       3186     3191       +5     
+ Partials      286      285       -1     

Files	Coverage Δ
src/ert/cli/model_factory.py	96.82% <ø> (ø)
src/ert/enkf_main.py	100.00% <100.00%> (ø)
.../gui/tools/manage_cases/case_init_configuration.py	96.26% <100.00%> (-0.14%)	⬇️
src/ert/run_models/base_run_model.py	94.46% <100.00%> (ø)
src/ert/run_models/ensemble_experiment.py	97.82% <ø> (ø)
src/ert/run_models/ensemble_smoother.py	100.00% <ø> (ø)
src/ert/run_models/iterated_ensemble_smoother.py	94.87% <100.00%> (-0.13%)	⬇️
src/ert/run_models/multiple_data_assimilation.py	89.10% <ø> (ø)
src/ert/run_models/run_arguments.py	100.00% <100.00%> (ø)
...rc/ert/gui/tools/run_analysis/run_analysis_tool.py	79.43% <66.66%> (-0.57%)	⬇️
... and 1 more

... and 3 files with indirect coverage changes

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