Add utility endpoint for e2e cypress testing

[whabanks]

Summary | Résumé

This PR adds a utility Admin endpoint that supports Cypress UI tests.

• Allow specifying a desired id when saving a callback so we can more easily manage test data in the DB
• The utility endpoint cleans up the service_callback_api and service_callback_api_history table in the DB

Related Issues | Cartes liées

• Task/callback UI tests notification-admin#1955

Test instructions | Instructions pour tester la modification

1. Pull down this PR and run it locally
2. Run the Cypress tests found in this PR

Release Instructions | Instructions pour le déploiement

None.

Reviewer checklist | Liste de vérification du réviseur

• This PR does not break existing functionality.
• This PR does not violate GCNotify's privacy policies.
• This PR does not raise new security concerns. Refer to our GC Notify Risk Register document on our Google drive.
• This PR does not significantly alter performance.
• Additional required documentation resulting of these changes is covered (such as the README, setup instructions, a related ADR or the technical documentation).

⚠ If boxes cannot be checked off before merging the PR, they should be moved to the "Release Instructions" section with appropriate steps required to verify before release. For example, changes to celery code may require tests on staging to verify that performance has not been affected.