Nodes themselves are not namespaced, so we'd originally assumed we did not need to pass through the ns query parameter when listing or viewing nodes.
As it turns out the API endpoints we use to list and view nodes (and related things) return things that are namespaced, therefore any API requests for nodes do require a the ns query parameter to be passed through to the request.
This PR adds the necessary ns query param to all things Node, apart from the querying for the leader which only returns node related information.
Additionally here we decided to show 0 Services text in the node listing if there are nodes with no service instances within the namespace you are viewing, as this is clearer than showing nothing at all. We also cleaned up/standardized the text we use to in the empty state for service instances.
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