[PATCH 0/1][focal/jammy/kinetic/lunar linux] Disable hv-kvp-daemon if /dev/vmbus/hv_kvp is not present

[Tim Gardner]

BugLink: https://bugs.launchpad.net/bugs/2024900

SRU Justification

[Impact]

If the hv-kvp daemon is started and the vmbus is not present it will just exit with an error:
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/mantic/tree/tools/hv/hv_kvp_daemon.c#n1424

Thus, it would make sense to add "ConditionPathExists=/dev/vmbus/hv_kvp" in
linux-cloud-tools-common.hv-kvp-daemon.service to prevent systemd from starting
the daemon if the device is not there.

[Test Plan]

Start an Azure cloud instance and check for /dev/vmbus/hv_kvp and that hv-kvp-daemon is running.
Start a non-Azure cloud instance and check that hv-kvp-daemon is not running.

[Regression potential]

Its possible that kv-hvp-daemon is not started when it should be.