Refactor audit events for Releases

What does this MR do and why?

Refactors Release services to use Gitlab::Audit::Auditor for creating audit events.

Adds the following event types:

• release_created
• release_updated
• release_deleted
• release_milestones_updated

Note: this MR does -not- remove the associated AuditEventService subclasses, as these are still used in other feature specs. Will verify that issue(s) exist to refactor these later.

How to set up and validate locally

Need API testing steps

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #374111 (closed)