systemd timesyncd is the default mechanism for timesync on Focal;
let's reduce our modification footprint by not overinstalling ntp or
trying to enable it.
These images are Python3 only -- no python-dev
The ntp tools are replaced with chrony on CentOS 8, select it instead.
Update the service enablement too. I have done a quick audit and
I don't believe any of our base job parts rely on ntpdate as such
(except for deprecated devstack-gate; there is actually an
unmerged ancient change! ).