Fix snmpit error after DeleteNodes()
Seen this a couple of times, deleting all nodes but a single node, which means deleting the vlan, results in this error:
stack::findVlans calling ms-chassis9-switchb
*** snmpit:
No vlanid 67208 in the DB!
Failed to setup vlans: Failed to synchronize vlans
See https://www.utah.cloudlab.us/spewlogfile.php3?logfile=1b1d96adb75be1ec12725cda2145a751