SSSDConfigTest: Test real config without config_file_version
src/config/testconfigs/sssd-valid.conf explicitly contains
config_file_version. Recently we changed the default value to 2
and therefore it needn't be listed in configuration file.
This patch test real sssd.conf without config_file_version.
Reviewed-by: Michal Židek <mzidek@redhat.com>
(cherry picked from commit 7388fc91bd6c22705e60632346ec815f4a4963f1)
(cherry picked from commit b1c6767617c082de2521976175bc2f499ec295e9)