Duplicate 'ignore-missing-schema-sources' in the NETCONF node

Currently there are two ignore-missing-schema-sources in the topology node for topology-netconf augmented from two modules:

• netconf-node-optional
• netconf-node-topology

Among those two, only the first one is used at all although there is no real effect other than generating a log message when allowed is set to true since the implementation was removed for v5.0.0 and hasn't been implemented yet (NETCONF-925).

Another issue is that when the ignore-missing-schema-sources parameters are configured using the netconf-node-topology:create-device RPC, the parameters are saved under the netconf-node-topology:ignore-missing-schema-sources node, hence it does not have any effect and won't have any effect even if the feature is implemented.