
L3 agent supports multiple external networks from a long time ago, so remove this RPC call since it is not used. According to codesearch of [1] and [2], we just remove neutron built-in L3 agent RPC. For neutron server side or RPC callback classes, the function is still remained. [1] http://codesearch.openstack.org/?q=get_external_network_id [2] http://codesearch.openstack.org/?q=L3RpcCallback Change-Id: I764423e175d6e82729a647e415a9f267f495916f Closes-Bug: #1844168