SYSDB: Make the usage of the filter more generic for search_ts_matches()
    
    In order to make this function re-usable in different parts of our code,
    let's start passing an already built filter to it instead of having the
    specific code building the name filter there.
    
    Related:
    https://pagure.io/SSSD/sssd/issue/3369
    
    Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    (cherry picked from commit 8ad57e17779b3ec60246ac58c1691ee15745084c)