R1:3e0391c574f2

Don't mark subscribes/mentions as "Lock Overridden"

Summary:
See PHI1209. When a task is in "Hard Lock" mode, it's still possible to apply some changes to it. Notably:

- You can subscribe/unsubscribe.
- You can mention it on another object.
- You can add a relationship from some other object to it (e.g., select it as a "Parent Task" for some other task).

Currently, these types of edits will show a "Lock Overridden" timeline emblem icon. However, they should not: you didn't override a lock to make…