Remove Vet Status feature toggle and extra code

[khenson-oddball]

Summary

• This change removes the profile_show_proof_of_veteran_status_eligible feature toggle for and extra code used for testing out API changes. This toggle and extra code is being removed because all testing has been completed successfully.
• I work on the IIR Product team and we currently own this feature.

Related issue(s)

• 1143

Testing done

• [x] New code is covered by unit tests
• The old behavior is the same as the new behavior, it is just no longer behind a feature toggle. Veterans are still able to view their Proof of Status card or receive an error message if not eligible.

Screenshots

Note: Optional

What areas of the site does it impact?

None

Acceptance criteria

• [x] I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• [x] No error nor warning in the console.
• [x] Events are being sent to the appropriate logging solution
• [x] Documentation has been updated (link to documentation)
• [x] No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• [x] Feature/bug has a monitor built into Datadog (if applicable)
• [x] If app impacted requires authentication, did you login to a local build and verify all authenticated routes work as expected
• [ ] I added a screenshot of the developed feature

Requested Feedback

(OPTIONAL)What should the reviewers know in addition to the above. Is there anything specific you wish the reviewer to assist with. Do you have any concerns with this PR, why?