systemd timed out waiting for the context device

[vholer]

When contextualization ISO isn't present (on VMware/EC2), the systemd service scripts can take longer time or fail. Service start script needs to be changed:

1. not to depend on dev-disk-by\x2dlabel-CONTEXT.device, but on local-fs.target(?)
2. or have separate service scripts for KVM and VMware (with e.g. ConditionVirtualization=vmware)
3. or have separate packages for each environment

https://forum.opennebula.org/t/context-device-start-timeout/4692