Add a meaningful audit event name for `username` in User

Problem to solve

Some audit events are named audit_operation. This isn't a descriptive name and makes it difficult to differentiated from other events.

Additional context is available in this epic and in the parent epic.

Proposal

Add a meaningful name for the username audit event's update action that can be used to differentiate it from other events.

Naming should follow the noun_verb format and use the past tense. For example ci_variable_created.

For events created with audit_changes we can pass the event name using the event_type argument.

audit_changes(:email, as: 'email address', event_type: 'email_address_added')

Also consider this MR as an example of how to do this.

Implementation plan

1. Add an meaningful event name to the username event in this file.
   • The name should follow the noun_verb format.
2. Update the associated specs is required.

Notes

• For instructions on how to setup your development environment.
• For any questions regarding audit events reach out to a member of the compliance group.