Migrate timemap/refcase dependent observations

[yngve-sk]

Overview of changes

• Remove REFCASE, TIME_MAP, and HISTORY_OBSERVATION from ERT
• Add tool to migrate older ERT configs so that information from REFCASE and TIME_MAP is embedded into the obs config
• GENERAL_OBSERVATION can now only be used with RESTART, usage of DATE, HOURS, DAYS can be migrated if there is a REFCASE or TIME_MAP in the ERT config.
• SUMMARY_OBSERVATION can now only be used with DATE, usage of RESTART, HOURS, DAYS can be migrated if there is a REFCASE or TIME_MAP in the ERT config.

Nice to know:

• Tests that were previously testing now deprecated behaviors have been kept by shimming the obs config migration into the test.
• Removed test case and logic for asserting that a SUMMARY_OBSERVATION's date matches up with the refcase / time map (this will be hard to pick up in migration, so suggest just dropping it)

Issue
Resolves #12619

[Copilot]

Pull request overview

This PR introduces a migration tool to convert deprecated HISTORY_OBSERVATION to SUMMARY_OBSERVATION and remove dependencies on TIME_MAP and REFCASE from observation configurations. The tool aims to help users migrate away from deprecated features as part of issue #12619.

Changes:

• Adds new ert_config_migrations.py module with observation migration logic
• Adds convert_observations CLI command to __main__.py

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 18 comments.

File	Description
src/ert/config/ert_config_migrations.py	New module implementing observation migration logic including text editing, observation conversion, and configuration parsing
src/ert/main.py	Adds CLI subcommand convert_observations to invoke the migration tool

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.64668% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.63%. Comparing base (f0d9de4) to head (9641e9d).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/ert/config/observation_config_migrations.py	94.08%	23 Missing ⚠️
src/ert/config/_observations.py	93.10%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12629      +/-   ##
==========================================
- Coverage   90.68%   90.63%   -0.05%     
==========================================
  Files         429      430       +1     
  Lines       29808    30068     +260     
==========================================
+ Hits        27030    27253     +223     
- Misses       2778     2815      +37     

Flag	Coverage Δ
cli-tests	37.33% <30.83%> (-0.23%)	⬇️
gui-tests	68.70% <32.54%> (-0.66%)	⬇️
performance-and-unit-tests	74.05% <92.93%> (+0.12%)	⬆️
test	37.59% <3.21%> (-0.48%)	⬇️

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[codspeed-hq]

Merging this PR will not alter performance

✅ 22 untouched benchmarks

---

_{Comparing yngve-sk:26.01.remove-history-obs-with-utility (90dd989) with main (0ac0ce1)}

[berland]

I think it is better to add :g to the value and error, to avoid an absolute value of 0.01 getting formatted as 0.099999123456 (it will prefer exponential format sometimes, but that is maybe fine enough here)

[yngve-sk]

It gives some discrepancy in test_that_history_observations_values_are_fetched_from_refcase, not sure anymore... Removed the commit temporarily to just have other tests pass, can add it back if we conclude it should be there.

[berland]

The documentation on HISTORY_OBSERVATION may also be deleted in this PR, as this keyword no longer works.

[oyvindeide]

Can do if that is most ideal? Was not sure whether we should do an inline edit to the ert config and not only the obs config. In the case that someone wants to add a new history obs, and then migrate it, removal of time map / refcase would block that.

Think that should be covered by tests, and it should be removed from snake_oil as that no longer has HISTORY_OBSERVATION.