Remove deprecated exposure types from schema definitions

[WilliamJamieson]

Resolves RAD-nnnn

Closes #606

This PR removes the outdated exposure types.

Tasks

• Update or add relevant rad tests.
• Update relevant docstrings and / or docs/ page.
• Does this PR change any schema files?
  • Schema changes were discussed at RAD Review Board meeting.
• Does this PR change any API used downstream? (If not, label with no-changelog-entry-needed.)
  • Write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see below for change types).
  • Start a romancal regression test (https://github.com/spacetelescope/RegressionTests/actions/workflows/romancal.yml) with this branch installed ("git+https://github.com/<fork>/rad@<branch>").
  • Update relevant roman_datamodels utilities and tests.

News fragment change types:

• changes/<PR#>.feature.rst: new feature
• changes/<PR#>.bugfix.rst: fixes an issue
• changes/<PR#>.doc.rst: documentation change
• changes/<PR#>.removal.rst: deprecation or removal of public API
• changes/<PR#>.misc.rst: infrastructure or miscellaneous change

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.73%. Comparing base (d2da141) to head (3ec9ead).
⚠️ Report is 137 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #636   +/-   ##
=======================================
  Coverage   96.73%   96.73%           
=======================================
  Files           8        8           
  Lines         644      644           
=======================================
  Hits          623      623           
  Misses         21       21           

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[PaulHuwe]

LGTM

[braingram]

Is there a new set of regression test files for this PR?

The scheduled run showed several failures:
https://github.com/spacetelescope/RegressionTests/actions/runs/16208770638
of the type:

failed on setup with "asdf._jsonschema.exceptions.ValidationError: 'WFI_GRISM' is not one of ['WFI_IMAGE', 'WFI_SPECTRAL', 'WFI_IM_DARK', 'WFI_SP_DARK', 'WFI_FLAT', 'WFI_LOLO', 'WFI_WFSC']

If these files aren't available can we revert this PR until they are? That way other roman work can continue to use the regtests?