Fix validation issues in PDF Generation

[opticbob]

Background

When trying to go through the appoint workflow for #92238 there were validation errors in the PDF generation step. Some of them require backend fixes. Front end fixes can be found in #92779 .

Tasks

• Convert submitted 3 character country codes to 2 character codes
• Fix claimant zip code suffix error for blank strings
• Take different paths through the workflow to see if any more validation errors can be triggered.

Acceptance Criteria

• A request body created by the frontend in staging will not trigger validation errors in the local environment
• New fixes will have tests