tests: fix import of correct_json_route_list
tests: fix import of correct_json_route_list

It got moved in de58d7d7c2f78274273847710adc3c1c255c78d5, let's import
it directly, not via examples/.

Change-Id: I0c36fcfdb775baac6fafc05ecd41ac39bafd750d

Telecominfraproject/gnpy