RCAL-802: Update outlier detection step to return a ModelContainer if input is an association file.

[mairanteodoro]

Resolves RCAL-802

This PR adds a unit test to ensure OutlierDetectionStep always return a ModelContainer with the updated datamodels. No changes to the step code were necessary.

Regression Tests https://plwishmaster.stsci.edu:8081/job/RT/job/Roman-Developers-Pull-Requests/724/

Checklist

• [ ] added entry in CHANGES.rst under the corresponding subsection
• [X] updated relevant tests
• [ ] updated relevant documentation
• [ ] updated relevant milestone(s)
• [X] added relevant label(s)
• [ ] ran regression tests, post a link to the Jenkins job below. How to run regression tests on a PR

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 79.55%. Comparing base (b61e70b) to head (f95298e). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1212 +/- ## ========================================== + Coverage 79.05% 79.55% +0.50% ========================================== Files 116 116 Lines 7994 7994 ========================================== + Hits 6320 6360 +40 + Misses 1674 1634 -40 ``` | [Flag](https://app.codecov.io/gh/spacetelescope/romancal/pull/1212/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spacetelescope) | Coverage Δ | | *Carryforward flag | |---|---|---|---| | [nightly](https://app.codecov.io/gh/spacetelescope/romancal/pull/1212/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spacetelescope) | `62.78% <ø> (ø)` | | Carriedforward from [e5841c6](https://app.codecov.io/gh/spacetelescope/romancal/commit/e5841c68bdd868d6997f051d8a412102cd2db4c6?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spacetelescope) | *This pull request uses carry forward flags. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spacetelescope) to find out more.

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