Remove Chronometer

[yubiuser]

What does this PR aim to accomplish?:

Removes Chronometer. It's not compatible with v6 as the telnet API is removed. We have a good and working replacement with https://github.com/pi-hole/PADD

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[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pihole-c-chronometer-throws-a-syntax-error/65510/3