peng - make extract multi to only handle the case of max_match > 1

Signed-off-by: Jialiang Liang <jiallian@amazon.com>

Author: RyanL1997

core/src/main/java/org/opensearch/sql/calcite/CalciteRelNodeVisitor.java

@@ -228,8 +228,7 @@ public RelNode visitRex(Rex node, CalcitePlanContext context) {
 
     for (int i = 0; i < namedGroups.size(); i++) {
       RexNode extractCall;
-      if (node.getMaxMatch().isPresent() && node.getMaxMatch().get() != 1) {
-        // Use REX_EXTRACT_MULTI for multiple matches
+      if (node.getMaxMatch().isPresent() && node.getMaxMatch().get() > 1) {
         extractCall =
             PPLFuncImpTable.INSTANCE.resolve(
                 context.rexBuilder,
@@ -239,7 +238,6 @@ public RelNode visitRex(Rex node, CalcitePlanContext context) {
                 context.relBuilder.literal(i + 1),
                 context.relBuilder.literal(node.getMaxMatch().get()));
       } else {
-        // Use REX_EXTRACT for single match (default)
         extractCall =
             PPLFuncImpTable.INSTANCE.resolve(
                 context.rexBuilder,