[TEST] split base settings in ClusterDiscoveryConfiguration between node and transport client

The default settings that are currently applied to the transport client are about discovery and gateway, modules that are not even loaded on the transport client. We can now remove the local gateway as it's the default one anyway. Also, let's make sure that the discovery setting is only applied to the node, as it is not relevant for transport client.
I see, I can put the discovery one back as constant but the name default is too generic cause they should get applied only to nodes and not used as base settings for transport client too.