topotests: bgp_evpn_rt5, configure route_distinguisher

topotests: bgp_evpn_rt5, configure route_distinguisher

When not configuring a route distinguisher, neither route-target,
the derived rd settings differ if config load applies with frr.conf
or not. For instance, the forged rd with frr.conf:

> # show bgp l2vpn evpn json
>    "192.168.101.41:3":{
>       "rd":"192.168.101.41:3",

and without:
>     "192.168.101.41:2":{
>        "rd":"192.168.101.41:2",

The defined rts also are impacted. Temporay fix this by using an
hardset configuration for all route distinguisher and route target
of the setups.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>