Remove form model filters

[neclimdul]

Remove form parameter schema filtering because some API's actually use this and are broken.

Fixes #6568

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[neclimdul]

I couldn't get the mvn commands to run cleanly in any branch, seeing what CI says.

Current state:

1. I expect this could use some tests around the use case in the related issue but I don't remember how to do that.
2. I left the method even though it isn't used. I don't know what the deprecation/removal policy would be.