Update datasource metadata to check for initial cluster state

Signed-off-by: acarbonetto <andrewc@bitquilltech.com>

datasources/src/main/java/org/opensearch/sql/datasources/storage/OpenSearchDataSourceMetadataStorage.java

@@ -80,7 +80,7 @@ public OpenSearchDataSourceMetadataStorage(
 
   @Override
   public List<DataSourceMetadata> getDataSourceMetadata() {
-    if (this.clusterService.state() == null) {
+    if (!this.clusterService.getClusterApplierService().isInitialClusterStateSet()) {
       return Collections.emptyList();
     }
     if (!this.clusterService.state().routingTable().hasIndex(DATASOURCE_INDEX_NAME)) {