Disable audit event logging for pipeline destruction

AuditEventService isn't equipped to handle logging of the destruction of entities such as CI pipelines. It's a project-level event that operates on a pipeline. The current log doesn't even indicate that the pipeline is being destroyed.

This is a CE backport of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9105. We're removing the auditing call because it breaks the EE implementation.