Audit dast schedule owner updates

What does this MR do and why?

Add the owner information to the list of auditable attributes updated by ee/app/services/app_sec/dast/profiles/update_service.rb .

The schedule owner is updated to the current user if it's not valid.

This update should be auditable.

Screenshots or screen recordings

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How to set up and validate locally

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

1. Follow the steps described here to trigger the owner update.

2. Check the audit table

audit_events = AuditEvent.where(target_id: dast_profile.dast_profile_schedule.id)
messages = audit_events.map(&:details).pluck(:custom_message)

[31] pry(main)> messages = audit_events.map(&:details).pluck(:custom_message)
=> ["Changed DAST profile schedule user_id from 100 to 1"]

MR acceptance checklist

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