core, miner, rpc, eth: fix goroutine leaks in tests (#24211)

* fix blocking and non-blocking issues

* core: revert change in blockchain.go

Co-authored-by: Martin Holst Swende <martin@swende.se>

node/node_test.go

@@ -393,7 +393,7 @@ func TestLifecycleTerminationGuarantee(t *testing.T) {
 // on the given prefix
 func TestRegisterHandler_Successful(t *testing.T) {
 	node := createNode(t, 7878, 7979)
-
+	defer node.Close()
 	// create and mount handler
 	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte("success"))