Junos node slicing: Ubuntu 20.04

The external server-based Junos node slicing supports Ubuntu 20.04 on the x86 servers. In Junos OS releases before Release 22.3R1, Junos node slicing supports Ubuntu 16.04. If you are currently running Ubuntu 16.04, we recommend that you upgrade your host OS to Ubuntu 20.04 before upgrading to Junos OS Release 22.3R1.