mem-cache: sizes of free and data tables were made consistent
    
    Since size of "free table" didn't account for SSS_AVG_*_PAYLOAD factor
    only small fraction of "data table" was actually used.
    SSS_AVG_*_PAYLOAD differentiation for different payload types only
    affected size of hash table and was removed as unjustified.
    
    Resolves: https://pagure.io/SSSD/sssd/issue/4160
    (cherry picked from PR999)
    
    Reviewed-by: Sumit Bose <sbose@redhat.com>
    
    Reviewed-by: Sumit Bose <sbose@redhat.com>