[fix](nereids) fix merge_percentile_to_array when has same agg functi…

…on (#44783)

Related PR: #34313

Problem Summary
The original PR did not handle the following scenario:
```sql
SELECT SUM(a), PERCENTILE(pk, 0.1) AS c1, PERCENTILE(pk, 0.1) AS c2, PERCENTILE(pk, 0.4) AS c3 FROM test_merge_percentile;
```
In this case, the aggregate outputs include two identical functions
(PERCENTILE(pk, 0.1)). When constructing the LogicalProject, a map was
used where the key is the child of an Alias and the value is the Alias
itself. However, this approach loses information when two Aliases share
the same child.
This PR modifies the map structure to use the child of an Alias as the
key and a list of Alias objects as the value. This ensures that all
Alias instances with the same child are preserved, resolving the issue
of lost information in such cases.

fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/MergePercentileToArray.java

@@ -152,10 +152,10 @@ private Plan doMerge(LogicalAggregate<Plan> aggregate) {
                 (List<Expression>) (List) newPercentileArrays);
         ImmutableList.Builder<NamedExpression> newProjectOutputExpressions = ImmutableList.builder();
         newProjectOutputExpressions.addAll((List<NamedExpression>) (List) notChangeForProject);
-        Map<Expression, Alias> existsAliasMap = Maps.newHashMap();
+        Map<Expression, List<Alias>> existsAliasMap = Maps.newHashMap();
         // existsAliasMap is used to keep upper plan refer the same expr
         for (Alias alias : existsAliases) {
-            existsAliasMap.put(alias.child(), alias);
+            existsAliasMap.computeIfAbsent(alias.child(), k -> new ArrayList<>()).add(alias);
         }
         Map<DistinctAndExpr, Slot> slotMap = Maps.newHashMap();
         // slotMap is used to find the correspondence
@@ -169,20 +169,22 @@ private Plan doMerge(LogicalAggregate<Plan> aggregate) {
         for (Map.Entry<DistinctAndExpr, List<AggregateFunction>> entry : funcMap.entrySet()) {
             for (int i = 0; i < entry.getValue().size(); i++) {
                 AggregateFunction aggFunc = entry.getValue().get(i);
-                Alias originAlias = existsAliasMap.get(aggFunc);
-                DistinctAndExpr distinctAndExpr = new DistinctAndExpr(aggFunc.child(0), aggFunc.isDistinct());
-                Alias newAlias = new Alias(originAlias.getExprId(), new ElementAt(slotMap.get(distinctAndExpr),
-                        new IntegerLiteral(i + 1)), originAlias.getName());
-                newProjectOutputExpressions.add(newAlias);
+                List<Alias> originAliases = existsAliasMap.get(aggFunc);
+                for (Alias originAlias : originAliases) {
+                    DistinctAndExpr distinctAndExpr = new DistinctAndExpr(aggFunc.child(0), aggFunc.isDistinct());
+                    Alias newAlias = new Alias(originAlias.getExprId(), new ElementAt(slotMap.get(distinctAndExpr),
+                            new IntegerLiteral(i + 1)), originAlias.getName());
+                    newProjectOutputExpressions.add(newAlias);
+                }
             }
         }
         newProjectOutputExpressions.addAll(groupBySlots);
-        return new LogicalProject(newProjectOutputExpressions.build(), newAggregate);
+        return new LogicalProject<>(newProjectOutputExpressions.build(), newAggregate);
     }
 
     private static class DistinctAndExpr {
-        private Expression expression;
-        private boolean isDistinct;
+        private final Expression expression;
+        private final boolean isDistinct;
 
         public DistinctAndExpr(Expression expression, boolean isDistinct) {
             this.expression = expression;
@@ -193,10 +195,6 @@ public Expression getExpression() {
             return expression;
         }
 
-        public boolean isDistinct() {
-            return isDistinct;
-        }
-
         @Override
         public boolean equals(Object o) {
             if (this == o) {

regression-test/data/nereids_rules_p0/merge_percentile_to_array/merge_percentile_to_array.out

@@ -41,3 +41,15 @@
 7.0	\N	\N
 7.0	7.0	7
 
+-- !same_percentile --
+52	1.0	1.0	2.0
+
+-- !same_percentile_group_by --
+\N	6.0	6.0	6.0
+2	3.0	3.0	3.0
+25	3.0	3.0	3.0
+4	2.0	2.0	2.0
+5	1.0	1.0	1.6
+7	6.0	6.0	6.0
+9	1.2	1.2	1.8
+

regression-test/suites/nereids_rules_p0/merge_percentile_to_array/merge_percentile_to_array.groovy

@@ -57,4 +57,8 @@ suite("merge_percentile_to_array") {
             percentile(abs(a), 0.55) as c2 from test_merge_percentile group by a) t;      
     """
 
+    order_qt_same_percentile """select sum(a),percentile(pk, 0.1) as c1 , percentile(pk, 0.1) as c2 ,
+            percentile(pk, 0.4) as c2 from test_merge_percentile;"""
+    order_qt_same_percentile_group_by """select sum(a),percentile(pk, 0.1) as c1 , percentile(pk, 0.1) as c2 ,
+            percentile(pk, 0.4) as c2 from test_merge_percentile group by a;"""
 }