Drop quantum dhcp lease update bin

In d9832282cf656b162c51afdefb830dacab72defe we dropped
the DHCP lease logic from neutron... including
the neutron-dhcp-agent-dnsmasq-lease-update.

Both the neutron and quantum bins were removed from setup.cfg
so we should also drop the quantum-dhcp-agent-dnsmasq-lease-update
as well.

Change-Id: I568845dc28aa4dc9012435de2f0689aafa00a43c