[acceptance tests] docker logs fetching is wrong with the new container names

[JordiSubira]

After #4396 the handling of scion prefixes and containers name is different. Scion service containers get started with the following name pattern: scion-<svc_id>-1, where <svc_id> is the service identifier, e.g. br1-ff00_0_1-1. However, when fetching the logs for the acceptance tests (https://github.com/scionproto/scion/blob/master/acceptance/common/docker.py#L61) the issued command is of the following form: docker logs svc_id, rendering the following error in the output dir for logs: Error response from daemon: No such container br1-ff00_0_1-1.