Event type information in deploy key audit event

What does this MR do and why?

Adds event type information in streamed audit events when deploy key is created/deleted on project level. below table list down event type names

action	event type
create/enable on project	deploy_key_added
remove/disabled on project	deploy_key_removed

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Setup external destination using https://docs.gitlab.com/ee/administration/audit_event_streaming.html#use-the-gitlab-ui or https://docs.gitlab.com/ee/administration/audit_event_streaming.html#use-the-api .
2. Go to Project -> Repository -> Deploy key
3. Create deploy key
4. Check audit event is created and streamed with correct event type. Also check audit event is visible at http://localhost:3000/admin/audit_logs and log is present in audit_json.log
5. Remove deploy key
6. repeat step 3
7. Go to Admin panel and create a deploy key
8. Enable this deploy key in project from Project -> Repository -> Deploy key
9. repeat step 3
10. Disable this deploy key in project from Project -> Repository -> Deploy key
11. repeat step 3

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 #363087 (closed)