State transfer enabled attribute is overridden by store fetch-state attribute

The decision whether to request state is made based on (configuration.clustering().stateTransfer().fetchInMemoryState() || configuration.persistence().fetchPersistentState()). In the XML fetchInMemoryState is <state-transfer enabled=X/>, fetchPersistentState is <store fetch-state=X/>.

We should rename fetchInMemoryState to match the XML and to indicate that it enables/disables all state transfer, and stores should not be allowed to fetch state if state transfer was disabled in the state transfer configuration.