With Debian 12+ the interactive zkCli.sh is completely broken, failing
to load the JLine module regardless of what is done, and no one in the
project seems to care about that.
Instead let's swap this out for the (non-interactive) GO-based zkcli of
https://github.com/go-zkcli/zkcli instead, as this suits our needs
nicely.
We're 100% systemd here, and the lack of control/information that the
old-school ZK initscript provides is frustrating. Replace it with our
own simple unit file.
Without this, the service seems to just loop failing to start
indefinitely even though PVC attempts to start the daemon itself.
Reenabling seems to work. Likely a bug due to Zookeeper not being
a proper systemd unit.
