routereflector: append some AS to show difference with and w/o RR
routereflector: ensure SRX are able to get a DHCP lease
routereflector: start nginx on DHCP to be able to "load replace" configurations
routereflector: force routing to some AS using MED
routereflector: don't use `next-hop self` but specify IP

The fact that we now get a valid IP on ge-0/0/0 seems to prevent
`next-hop self` to work as expected.
routereflector: use a virtual router to avoid DHCP default route