Refactor observation tests to stop using ErtConfig.observations

[eqbech]

Issue
Resolves #12751

Approach
Refactored a couple of tests to utilize make_observation and create_observation_dataframe instead of the ErtConfig.observations property. The helper function make_observation inside test_observations.py has been renamed to ert_config_from_parser and changed to now only parse obs config via parse_observations.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.71%. Comparing base (ee41291) to head (9e317fb).
⚠️ Report is 5 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12761      +/-   ##
==========================================
+ Coverage   90.68%   90.71%   +0.02%     
==========================================
  Files         433      434       +1     
  Lines       30239    30243       +4     
==========================================
+ Hits        27422    27434      +12     
+ Misses       2817     2809       -8     

Flag	Coverage Δ
cli-tests	37.16% <100.00%> (+<0.01%)	⬆️
gui-tests	68.54% <100.00%> (+<0.01%)	⬆️
performance-and-unit-tests	77.11% <100.00%> (+0.02%)	⬆️
test	37.47% <50.00%> (+0.01%)	⬆️

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[codspeed-hq]

Merging this PR will not alter performance

✅ 23 untouched benchmarks

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_{Comparing eqbech:update-tests-to-no-longer-use-ertconfig-observations (9e317fb) with main (c598863)}

[andreas-el]

Very nice work! 🥇
Please remember to squash the commits, and make sure that any spelling errors and such are removed.

[yngve-sk]

What usages of ErtConfig.observations remain? If none, you can remove the property 🎉 from ErtConfig (double check it is also not used in semeio or in other EQN repos, I'm not seeing any usages from searching our : https://github.com/search?q=org%3Aequinor%20.observations&type=code ) at least.

[eqbech]

What usages of ErtConfig.observations remain? If none, you can remove the property 🎉 from ErtConfig (double check it is also not used in semeio or in other EQN repos, I'm not seeing any usages from searching our : https://github.com/search?q=org%3Aequinor%20.observations&type=code ) at least.

Have removed observations from ErtConfig and updated associated tests.

[yngve-sk]

Nice, LGTM!