Improve tenant recovery mechanism
Improve tenant recovery mechanism

When resetting the ACI tenants, sometimes the thread could be hanging
and scheduling a tree reset woulnd't be enough. Kill the tenant thread
and garbage collect the tenant handler instead, so that AID can
re-provision it on the next iteration and hopefully be able to
properly sync.

noironetworks/aci-integration-module,noironetworks/aci-integration-module