[CORE] Remove Restart API and remove Node#stop()

The restart API seems pretty esoteric and is entirely untested.
This commit removes it without a replacement.

Closes #9841

src/main/java/org/elasticsearch/action/ActionModule.java

@@ -28,8 +28,6 @@
 import org.elasticsearch.action.admin.cluster.node.info.NodesInfoAction;
 import org.elasticsearch.action.admin.cluster.node.info.TransportNodesInfoAction;
 import org.elasticsearch.action.admin.cluster.node.liveness.TransportLivenessAction;
-import org.elasticsearch.action.admin.cluster.node.restart.NodesRestartAction;
-import org.elasticsearch.action.admin.cluster.node.restart.TransportNodesRestartAction;
 import org.elasticsearch.action.admin.cluster.node.shutdown.NodesShutdownAction;
 import org.elasticsearch.action.admin.cluster.node.shutdown.TransportNodesShutdownAction;
 import org.elasticsearch.action.admin.cluster.node.stats.NodesStatsAction;
@@ -228,7 +226,6 @@ protected void configure() {
         registerAction(NodesInfoAction.INSTANCE, TransportNodesInfoAction.class);
         registerAction(NodesStatsAction.INSTANCE, TransportNodesStatsAction.class);
         registerAction(NodesShutdownAction.INSTANCE, TransportNodesShutdownAction.class);
-        registerAction(NodesRestartAction.INSTANCE, TransportNodesRestartAction.class);
         registerAction(NodesHotThreadsAction.INSTANCE, TransportNodesHotThreadsAction.class);
 
         registerAction(ClusterStatsAction.INSTANCE, TransportClusterStatsAction.class);