kolab_api_service: fix typo in variable name
Summary: Fixes typo to make object_type detection works again. This fixes T6694
Test Plan:
Create a shared calendar folder via webadmin. Try to edit
the previously created shared folder. The form for shared addressbook
and its title is shown.
Reviewers: Web Administration Panel Developers, vanmeeuwen, machniak
Reviewed By: Web Administration Panel Developers, machniak
Maniphest Tasks: T6694
Differential Revision: https://git.kolab.org/D2860