remove useless change

Signed-off-by: xinyual <xinyual@amazon.com>

Author: xinyual

core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java

@@ -234,7 +234,6 @@ void populate() {
       registerOperator(IS_NULL, SqlStdOperatorTable.IS_NULL);
       registerOperator(IF, SqlStdOperatorTable.CASE);
       registerOperator(IFNULL, SqlStdOperatorTable.COALESCE);
-      registerOperator(IS_PRESENT, SqlStdOperatorTable.IS_NOT_NULL);
       registerOperator(EARLIEST, PPLBuiltinOperators.EARLIEST);
       registerOperator(LATEST, PPLBuiltinOperators.LATEST);
       registerOperator(COALESCE, SqlStdOperatorTable.COALESCE);