`TransportGetShutdownStatusAction` has a few checks that prevents the node from being shut down if there are shards without a copy that we can't move. We should also check that whether the node has unassigned shard and if it does, return the `STALLED` status and prevent the node from being shut down.

Relates #73873, #78578
x-pack/plugin/shutdown/src/internalClusterTest/java/org/elasticsearch/xpack/shutdown/NodeShutdownShardsIT.java
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */
package org.elasticsearch.xpack.shutdown;
import org.elasticsearch.Build;
import org.elasticsearch.action.admin.cluster.allocation.ClusterAllocationExplainResponse;
import org.elasticsearch.action.admin.cluster.node.info.NodeInfo;
import org.elasticsearch.action.admin.cluster.node.info.NodesInfoResponse;