Fix non working update dynamic settings

Described in elastic/elasticsearch#10614, it's not possible with cloud discovery plugin to update dynamic settings anymore.

```sh
curl -XPUT localhost:9200/_cluster/settings -d '{
    "persistent" : {
        "discovery.zen.minimum_master_nodes" : 3
    },
    "transient" : {
        "discovery.zen.minimum_master_nodes" : 3
    }
}'
```

gives

```json
{"acknowledged":true,"persistent":{},"transient":{}}
```

Closes #80.

Author: dadoonet

src/main/java/org/elasticsearch/discovery/azure/AzureDiscovery.java

@@ -24,6 +24,7 @@
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.cluster.ClusterService;
 import org.elasticsearch.cluster.node.DiscoveryNodeService;
+import org.elasticsearch.cluster.settings.ClusterDynamicSettings;
 import org.elasticsearch.cluster.settings.DynamicSettings;
 import org.elasticsearch.common.collect.ImmutableList;
 import org.elasticsearch.common.inject.Inject;
@@ -50,7 +51,7 @@ public class AzureDiscovery extends ZenDiscovery {
     public AzureDiscovery(Settings settings, ClusterName clusterName, ThreadPool threadPool, TransportService transportService,
                           ClusterService clusterService, NodeSettingsService nodeSettingsService, ZenPingService pingService,
                           DiscoveryNodeService discoveryNodeService, AzureComputeService azureService, NetworkService networkService,
-                          DiscoverySettings discoverySettings, ElectMasterService electMasterService, DynamicSettings dynamicSettings,
+                          DiscoverySettings discoverySettings, ElectMasterService electMasterService, @ClusterDynamicSettings DynamicSettings dynamicSettings,
                           Version version) {
         super(settings, clusterName, threadPool, transportService, clusterService, nodeSettingsService,
                 discoveryNodeService, pingService, electMasterService, discoverySettings, dynamicSettings);