[3.3] Optimize TriRpcStatus by adding http status code to its description (#15708)

* Optimize TriRpcStatus by adding http status code to its description

* Fix dubboCodeToTriCode method by converting METHOD_NOT_FOUND to UNIMPLEMENTED

* Add back invalid keyword to TriRpcStatus description at validateHeaderStatus method

Author: zrlw

dubbo-rpc/dubbo-rpc-triple/src/main/java/org/apache/dubbo/rpc/TriRpcStatus.java

@@ -135,7 +135,7 @@ public static Code dubboCodeToTriCode(int rpcExceptionCode) {
                 code = Code.UNAVAILABLE;
                 break;
             case METHOD_NOT_FOUND:
-                code = Code.NOT_FOUND;
+                code = Code.UNIMPLEMENTED;
                 break;
             case SERIALIZATION_EXCEPTION:
                 code = Code.INTERNAL;

dubbo-rpc/dubbo-rpc-triple/src/main/java/org/apache/dubbo/rpc/protocol/tri/stream/AbstractTripleClientStream.java

@@ -244,7 +244,7 @@ private TriRpcStatus validateHeaderStatus(Http2Headers headers) {
             final CharSequence contentType = headers.get(HttpHeaderNames.CONTENT_TYPE.getKey());
             if (contentType == null || !GrpcUtils.isGrpcRequest(contentType.toString())) {
                 return TriRpcStatus.fromCode(TriRpcStatus.httpStatusToGrpcCode(httpStatus))
-                        .withDescription("invalid content-type: " + contentType);
+                        .withDescription("HTTP status: " + httpStatus + ", invalid content-type: " + contentType);
             }
             return null;
         }