R1:75dfae10118a

Don't require any special capabilities to apply a "closed a subtask" transaction to a parent task

Summary:
See PHI1059. If you close a task, we apply an "alice closed a subtask: X" transaction to its parents.

This transaction is purely informative, but currently requires `CAN_EDIT` permission after T13186. However, we'd prefer to post this transaction anyway, even if: the parent is locked; or the parent is not editable by the acting user.

Replace the implicit `CAN_EDIT` requirement with no requirement.