Use macros and don't call systemctl directly
- Resolves: rhbz#850328 - Introduce new systemd-rpm macros in sssd spec file
(cherry picked from commit 94f4c4dd6d20757bb9f04b90f4deb99dce3f2729)
(cherry picked from commit 86b6a6851e632d5372d2da5500ead24982ec44f7)