[bugfix] [RHEL-7] Version 2 of RHEL-7 update service macros in shorthand2xccdf.xsl XSLT transformation

This change updates the form of:
<ul>
<li>    service-disable-macro, </li>
<li>    service-enable-macro, </li>
<li>   service-disable-check-macro, </li>
<li>    xinetd-service-disable-check-macro, and </li>
<li>    service-enable-check-macro </li>
</ul>
in order they to start using the form to read as ```# systemctl ... ```rather than ```# chkconfig ...```

Also update the 'Disable telnet Service' XCCDF rule description not to use the service-disable-macro (since the default form can't be used for telnet service on RHEL-7. We need a custom one for telnet).

Tested on RHEL-7 & works as expected.

Please review.

Thanks, Jan.

--

Version #2: Fixes issue from previous version (replace ```<code> </code>``` elements in telnet service changes with ```<tt> </tt>``` elements).