Use 389-ds provided method for file limits tuning
    
    Previously IPA would set the LimitNOFILE value to 8192 to increase
    the number of concurrent clients. 389-ds-base does this by default
    as of 1.3.7.0.
    
    Remove the IPA-specific tuning and rely on the out-of-the-box
    389-ds-base tuning.
    
    Bump the required version of 389-ds-base to 1.3.7.0.
    
    Any other tuning added by 389-ds-base will result in a
    dirsrv.systemd.rpmsave file which admins will need to merge
    in manually, like typical .rpmsave config changes.
    
    https://pagure.io/freeipa/issue/6994
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>