add traceID field and spanID field (#4066)

Signed-off-by: Xiangyu Zhu <[email protected]>

Author: Frefreak

cmd/pdatagen/internal/metrics_structs.go

@@ -316,6 +316,8 @@ var exemplar = &messageValueStruct{
 			originFieldName: "FilteredAttributes",
 			returnSlice:     attributeMap,
 		},
+		traceIDField,
+		spanIDField,
 	},
 }