Update IT

Signed-off-by: Peng Huo <penghuo@gmail.com>

Author: penghuo

integ-test/src/test/java/org/opensearch/sql/ppl/SystemFunctionIT.java

@@ -89,7 +89,7 @@ public void typeof_opensearch_types() throws IOException {
             "TIMESTAMP",
             "TIMESTAMP",
             "BOOLEAN",
-            "OBJECT",
+            "STRUCT",
             "STRING",
             "IP",
             "BINARY",