Prevent creation of todos when a task list is checked in an epic

Problem To Solve

In an epic with a checklist in the description where a user's handle is next to a checklist item, checking any box in the checklist creates a todo for everyone else. It should not behave this way as the user already has a todo for the epic created the first time they are referenced in the description.

Note: This only happens for epics and is inconsistent with the behavior in issues and MRs. We skip todo creation when toggling tasks in issues / MRs.

Expected Behavior

• When your handle is included next to a checklist item, a todo should be created.
• When your name is checked off, the todo should be closed.
• User A should never receive a todo when another User B checks off User B's name.

Example epic -- &5016