mod_ssl: add SSLVerifyDepth for external CA installs
    
    mod_ssl's limiting of client cert verification depth was causing
    the replica installs to fail when master had been installed with
    external CA since the SSLCACertificateFile was pointing to a file
    with more than one certificate. This is caused by the default
    SSLVerifyDepth value of 1. We set it to 5 as that should be
    just about enough even for possible sub-CAs.
    
    https://pagure.io/freeipa/issue/7530
    
    Reviewed-By: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>