Node shutdown test integration test (elastic#114582)

This change adds a test case that verifies that the node
can be shutdown while hosting an index with 0-1 or 0-all
auto-expand configuration.

x-pack/plugin/shutdown/src/internalClusterTest/java/org/elasticsearch/xpack/shutdown/NodeShutdownShardsIT.java

@@ -375,6 +375,32 @@ public void testAutoExpandDuringReplace() throws Exception {
         assertIndexSetting("index", "index.number_of_replicas", "1");
     }
 
+    public void testAutoExpandDuringShutdown() throws Exception {
+
+        var node1 = internalCluster().startNode();
+        var node2 = internalCluster().startNode();
+
+        createIndex("index", indexSettings(1, 0).put("index.auto_expand_replicas", randomFrom("0-all", "0-1")).build());
+        indexRandomData("index");
+
+        ensureGreen("index");
+        assertIndexSetting("index", "index.number_of_replicas", "1");
+
+        var nodeNameToShutdown = randomFrom(node1, node2);
+        var nodeIdToShutdown = getNodeId(nodeNameToShutdown);
+
+        putNodeShutdown(nodeIdToShutdown, SingleNodeShutdownMetadata.Type.REMOVE, null);
+
+        ensureGreen("index");
+        assertIndexSetting("index", "index.number_of_replicas", "0");
+
+        assertBusy(() -> assertNodeShutdownStatus(nodeIdToShutdown, COMPLETE));
+        internalCluster().stopNode(nodeIdToShutdown);
+
+        ensureGreen("index");
+        assertIndexSetting("index", "index.number_of_replicas", "0");
+    }
+
     public void testNodeShutdownWithUnassignedShards() throws Exception {
         final String nodeA = internalCluster().startNode();
         final String nodeAId = getNodeId(nodeA);