Use @ syntax for zone apex
Summary:
That syntax makes kzonecheck happy and allow to pass D3690 tests.
This is a follow-up for f69c1d980c73.
This is a follow-up for ac2654f0e48a.
Ref T1217
Test Plan: kzonecheck
Reviewers: DorianWinty
Reviewed By: DorianWinty
Maniphest Tasks: T1217
Differential Revision: https://devcentral.nasqueron.org/D3691