tests: validate if node with old node is is reported as offline

The node folder deletion test checks if a node joins the cluster with
the new node id after its data folder was deleted. Introduced a new
validation checking if in this case the node with the old node_id
is reported as offline

Signed-off-by: Michał Maślanka <michal@redpanda.com>

tests/rptest/tests/node_folder_deletion_test.py

@@ -94,7 +94,22 @@ def test_deleting_node_folder(self):
         wait_until(lambda: producer.produce_status.acked > 200000,
                    timeout_sec=120,
                    backoff_sec=0.5)
+
         admin = Admin(self.redpanda)
+
+        # validate that the node with deleted folder is recognized as offline
+        def removed_node_is_reported_offline():
+            cluster_health = admin.get_cluster_health_overview()
+            return id in cluster_health['nodes_down']
+
+        wait_until(
+            removed_node_is_reported_offline,
+            timeout_sec=20,
+            backoff_sec=0.5,
+            err_msg=
+            f"Node {id} is expected to be marked as offline as it was replaced by new node"
+        )
+
         # decommission a node that has been cleared
         admin.decommission_broker(id)
         waiter = NodeDecommissionWaiter(self.redpanda,