Remove extra code in allocation commands parsing (#53579)

This commit removes some code that is duplicated in the parsing of
allocation commands in the cluster reroute API.

Author: jasontedor

server/src/main/java/org/elasticsearch/cluster/routing/allocation/command/AllocationCommands.java

@@ -137,9 +137,6 @@ public static AllocationCommands fromXContent(XContentParser parser) throws IOEx
             throw new ElasticsearchParseException("No commands");
         }
         if (token == XContentParser.Token.FIELD_NAME) {
-            if (!parser.currentName().equals("commands")) {
-                throw new ElasticsearchParseException("expected field name to be named [commands], got [{}] instead", parser.currentName());
-            }
             if (!parser.currentName().equals("commands")) {
                 throw new ElasticsearchParseException("expected field name to be named [commands], got [{}] instead", parser.currentName());
             }