[SSSD] [PATCH] Providers cleanup: Remove unused parameters

During the nested initgroups processing review, Jan requested removing unused "dom" parameter from the code. Instead of doing it on that one place, I compiled SSSD with -Wunused and cleaned up unused parameters in the providers code. It's mostly sss_domain_info no longer needed because of the sysdb refactoring. The patch brings no functional change, it's just cleanup.