ONOS-2846, ONOS-2812 Refactored link discovery pruning to be centralized rather than being with each link discovery helper.

This will make it behave properly in a distributed context.

Change-Id: I9b9788336468c41d1cf506e388306ad9136d5853
diff --git a/tools/test/cells/office b/tools/test/cells/office
index 2cd933e..2e282c6 100644
--- a/tools/test/cells/office
+++ b/tools/test/cells/office
@@ -3,5 +3,6 @@
 export ONOS_NIC="10.1.10.*"
 export OC1="10.1.10.223"
 
+unset ONOS_USE_SSH
 export ONOS_APPS="drivers,openflow,fwd,proxyarp,mobility"