Remove AuditEvent retention policy from documentation

After more discussion we have decided to defer adding the AuditEvent
retention policy to the documentation until we can make a coordinated
announcement about this policy, especially with details about exactly
when actual data deletion will commence in the future.

doc/administration/audit_events.md

@@ -180,12 +180,6 @@ the steps bellow.
    Feature.enable(:repository_push_audit_event)
    ```
 
-## Retention policy
-
-On GitLab.com, Audit Event records become subject to deletion after 400 days, or when your license is downgraded to a tier that does not include access to Audit Events. Data that is subject to deletion will be deleted at GitLab's discretion, possibly without additional notice.
-
-If you require a longer retention period, you should independently archive your Audit Event data, which you can retrieve through the [Audit Events API](../api/audit_events.md).
-
 ## Export to CSV **(PREMIUM ONLY)**
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/1449) in [GitLab Premium](https://about.gitlab.com/pricing/) 13.4.