Remove `access_token_pagination` feature flag

What does this MR do and why?

Remove access_token_pagination feature flag

We have deemed the access_token_pagination feature flag stable and we proceed to remove it here.

• Introduced by: !91372 (merged)
• rollout issue: #366534 (closed)

Changelog: changed

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.

Screenshots or screen recordings

N/A

How to set up and validate locally

The personal, group, project and impersonation token pages should continue to work normally. If there are more than 20 personal, group, project access tokens, a pagination component should be seen.

See instructions here