Requires GitLab Testing Agreement on Self-Hosted Configuration

What does this MR do and why?

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Database

main: == [advisory_lock_connection] object_id: 118100, pg_backend_pid: 27477
main: == 20240605120629 CreateAiTestingTermsAcceptances: migrating ==================
main: -- create_table(:ai_testing_terms_acceptances)
main: -- quote_column_name(:user_email)
main:    -> 0.0000s
main:    -> 0.0037s
main: == 20240605120629 CreateAiTestingTermsAcceptances: migrated (0.0255s) =========

main: == [advisory_lock_connection] object_id: 118100, pg_backend_pid: 27477
ci: == [advisory_lock_connection] object_id: 118360, pg_backend_pid: 27479
ci: == 20240605120629 CreateAiTestingTermsAcceptances: migrating ==================
ci: -- create_table(:ai_testing_terms_acceptances)
ci: -- quote_column_name(:user_email)
ci:    -> 0.0000s
ci:    -> 0.0064s
I, [2024-06-06T13:20:14.006731 #27291]  INFO -- : Database: 'ci', Table: 'ai_testing_terms_acceptances': Lock Writes
ci: == 20240605120629 CreateAiTestingTermsAcceptances: migrated (0.0181s) =========

ci: == [advisory_lock_connection] object_id: 118360, pg_backend_pid: 27479```

Down:

main: == [advisory_lock_connection] object_id: 125840, pg_backend_pid: 20271
main: == 20240604150537 QueueBackfillVulnerabilityUserMentionsProjectId: reverting ==
main: == 20240604150537 QueueBackfillVulnerabilityUserMentionsProjectId: reverted (0.0308s)

main: == [advisory_lock_connection] object_id: 125840, pg_backend_pid: 20271

Query:

SELECT 1 AS one FROM "ai_testing_terms_acceptances" LIMIT 1

Screenshots or screen recordings

2024-06-06_13.50.21

How to set up and validate locally

1. Enable self-hosted models:

   Feature.enable(:ai_custom_models)

2. Make sure you are running as SaaS. On GDK navigate to the admin area, select Ai Feature, and Models. It should open the page to accept the terms. Once accepted, it should redirect to the index page.

3. Try opening clicking on models again, this time the accept terms shouldn't be shown

Related to #464361 (closed)