Treat validation variables as globals (source: 18F/fedramp-automation: 582)

[danielnaab]

Original issue: 18F#582

Extended Description
To prep for SchXslt usage, replace local variables usage with globals. Discovered by #529

Acceptance Criteria

• Local variables with duplicate names removed.

Definition of Done

• Acceptance criteria met
• Unit test coverage of our code > 90% - needs automation story
• Accessibility tests pass - needs automation story
• Automated code quality checks pass
• Security reviewed and reported - check in with Wes on what we could do here
• Reviewed against plain language guidelines
• Design QA passed
• Code must be self-documenting
• No local tech debt
• Documentation updated
• Architectural Decision Record completed as necessary for significant design choices
• PR reviewed & approved
• Source code merged

[aj-stein-gsa]

Re ADR 7, we will not use the previous constraint architecture as-is and the relevant code will soon be removed. I am closing this issue as not planned.