Only produce `ScheduleCreateOutput#scheduleID` on `IDENTICAL_SCHEDULE_ALREADY_CREATED`

### Problem

If a `ScheduleCreate` gets `SUCCESS`, it will have a `StateChange` item that shows the id of the created schedule. This means there is no need to set the `CreateScheduleOutput#schedule_id` field in this case.

### Solution

Only set this field when the final status is `IDENTICAL_SCHEDULE_ALREADY_CREATED`.

### Alternatives

_No response_

Start by locating the ScheduleCreate handling and the code that populates CreateScheduleOutput#schedule_id and StateChange items. Trace the final status handling, especially SUCCESS and IDENTICAL_SCHEDULE_ALREADY_CREATED. Done means schedule_id is produced only for IDENTICAL_SCHEDULE_ALREADY_CREATED, while SUCCESS exposes the created schedule ID through StateChange.

Written by the indexing model from the issue text.