Overview:
Send l3vpn route from external peer 1 through play.py.

Send route-target route with specific rt argument from previous route from external peer 2.

Route l3vpn is present on peer 2 in adj-rib-out.

Remove route-target route from odl by sending specific rt argument from peer 2. 

Expect odl to remove the l3vpn route from peer 2 with update message, and also from adj-rib-out.

Steps to reproduce:
1. Start odl with usual features:

feature:install odl-restconf odl-bgpcep-bgp odl-bgpcep-bgp-config-example

2. Configure ebgp peer 1 with 127.0.0.2 IP and 1 ibgp peer 2 with 127.0.0.3 IP

./configure.py

3. Start play.py's

./start_play1.sh
./start_play2.sh

4. Send l3vpn route from first play, and than route-target route from second play

./send_route_from_play1.py
./send_route_from_play2.py

5. Remove route-target route from odl by sending specific rt argument from peer 2.

./remove_route_from_play2.py