R1:f45519c0604b

When cancelling an inline comment edit, exit the edit state after the response arrives

Summary: Ref T13513. This fixes a bug where clicking a line number, then clicking "Cancel" causes the paths panel to briefly update with an extra inline comment counted on the file.

Test Plan:
- Clicked a line number.
- Typed some text.
- Clicked "Cancel".
- Before patch: paths panel flashes "1".
- After patch: paths panel stays stable.

Maniphest Tasks: T13513

Differential Revision: https://secure.