Revert "pl-fe: migrate /api/v*/instance to tanstack query"

This reverts commit 1f8b79f309.

packages/pl-fe/src/hooks/use-instance.ts

@@ -0,0 +1,6 @@
+import { useAppSelector } from './use-app-selector';
+
+/** Get the Instance for the current backend. */
+const useInstance = () => useAppSelector((state) => state.instance);
+
+export { useInstance };