Geo rake check: include hostname of NTP source when `Machine clock is synchronized` fails

Proposal

When the Geo rake check fails to verify NTP ..

Machine clock is synchronized ... Exception: Timeout::Error
Machine clock is synchronized ... Exception: No route to host - recvfrom(2)

It's not obvious that it's calling pool.ntp.org

This based on the analysis in a customer ticket (internal link) that the NTP check will be run against the default NTP server of pool.ntp.org as we can see in the net-ntp gem source.

Please can we update the output to include the hostname, like we did in gitaly!4916 (merged)

This will help if folks have to work around this using /etc/hosts per #381422 (closed)

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code is here