SYSDB: Split sysdb_try_to_find_expected_dn() into smaller functions
The function sysdb_try_to_find_expected_dn was performing several matching
algorithms and thus it was getting big and hard to extend. This patch
doesn't contain any functional changes, only shuffles the code around
and splits the monolithic sysdb_try_to_find_expected_dn function into
smaller blocks.
Reviewed-by: Sumit Bose <sbose@redhat.com>