We keep referencing Vyatta even though Vyatta Core is long dead.
A good first step to get rid of this is to create vyos_* environment variables equivalent to vyatta_bindir, vyatta_sbindir etc.
A good next step would be to replace hardcoded /opt/vyatta references to these variables. A perfect step after this would be to keep the variables in a config files rather than a shell script that could be read by all VyOS programs. But let's start with simply duplicating them for now.