BS: Start discovery runner separate from other tasks (#2714)
BS: Start discovery runner separate from other tasks (#2714)

Discovery runner is not a BS specific task and therefore doesn't belong to the BS task group.
Oncilla/scion,Oncilla/scion,Oncilla/scion,netsec-ethz/scion,netsec-ethz/scion,Oncilla/scion,netsec-ethz/scion,netsec-ethz/scion