selinux: Keep explicite umask() calls
libsemanage < 2.6 use to not set right file mask in our usecase.
It has been fixed by manual umask() call but is no longer needed.
Fix will be keept as a precaution for future libsemanage versions.
Resolves:
https://pagure.io/SSSD/sssd/issue/3583
Reviewed-by: Pavel Březina <pbrezina@redhat.com>