Disable Schema Compat plugin during server upgrade
    
    If this is enabled it can cause a deadlock with SSSD trying
    to look up entries and it trying to get data on AD users
    from SSSD.
    
    When reading the entry from LDIF try to get the camel-case
    nsslapd-pluginEnabled and fall back to the all lower-case
    nsslapd-pluginenabled if that is not found. It would be nice
    if the fetch function was case sensitive but this is likely
    overkill as it is, but better safe than blowing up.
    
    Upon restoring it will always write the camel-case version.
    
    https://pagure.io/freeipa/issue/6721
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>