HLA-1587: Ignore distortion header keywords when comparing test WCS solutions

[s-goldman]

Resolves HLA-1587

Closes #

This PR addresses an issue arising from astropy PR #19228. That PR enables the ability to load a secondary WCS with that secondary's distortion correction. Since this is not something we regularly do, we can generally ignore this change as the primary distortion is almost always used for HST.

#19228 does change some code behavior in that when a secondary WCS solution is applied, the WCS solution will not have values for the header keywords cpdis1 or cpdis2.

The astropy PR was causing one of our tests to fail test_apply_as_alternate_method because the test was looking to make sure all relevant header keywords were the same. Since the cpdis keywords were None when applying a secondary, this was causing the failure. The solution is introduce a ignore_cpdis argument for the tests applying a secondary.

Checklist for maintainers

• added entry in CHANGELOG.rst within the relevant release section
• updated or added relevant tests
• updated relevant documentation
• added relevant label(s)