[fix](nereids)fix nullable property of ForEachCombinator (#37980)

## Proposed changes

pick from master #37796

<!--Describe your changes.-->

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/combinator/ForEachCombinator.java

@@ -20,9 +20,9 @@
 import org.apache.doris.catalog.FunctionSignature;
 import org.apache.doris.nereids.trees.expressions.Expression;
 import org.apache.doris.nereids.trees.expressions.functions.AggCombinerFunctionBuilder;
-import org.apache.doris.nereids.trees.expressions.functions.AlwaysNullable;
 import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
 import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunction;
+import org.apache.doris.nereids.trees.expressions.functions.agg.NullableAggregateFunction;
 import org.apache.doris.nereids.trees.expressions.shape.UnaryExpression;
 import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
 import org.apache.doris.nereids.types.ArrayType;
@@ -36,16 +36,20 @@
 /**
  * combinator foreach
  */
-public class ForEachCombinator extends AggregateFunction
-        implements UnaryExpression, ExplicitlyCastableSignature, AlwaysNullable, Combinator {
+public class ForEachCombinator extends NullableAggregateFunction
+        implements UnaryExpression, ExplicitlyCastableSignature, Combinator {
 
     private final AggregateFunction nested;
 
     /**
      * constructor of ForEachCombinator
      */
     public ForEachCombinator(List<Expression> arguments, AggregateFunction nested) {
-        super(nested.getName() + AggCombinerFunctionBuilder.FOREACH_SUFFIX, arguments);
+        this(arguments, false, nested);
+    }
+
+    public ForEachCombinator(List<Expression> arguments, boolean alwaysNullable, AggregateFunction nested) {
+        super(nested.getName() + AggCombinerFunctionBuilder.FOREACH_SUFFIX, false, alwaysNullable, arguments);
 
         this.nested = Objects.requireNonNull(nested, "nested can not be null");
     }
@@ -56,7 +60,7 @@ public static ForEachCombinator create(AggregateFunction nested) {
 
     @Override
     public ForEachCombinator withChildren(List<Expression> children) {
-        return new ForEachCombinator(children, nested);
+        return new ForEachCombinator(children, alwaysNullable, nested);
     }
 
     @Override
@@ -88,4 +92,9 @@ public AggregateFunction getNestedFunction() {
     public AggregateFunction withDistinctAndChildren(boolean distinct, List<Expression> children) {
         throw new UnsupportedOperationException("Unimplemented method 'withDistinctAndChildren'");
     }
+
+    @Override
+    public NullableAggregateFunction withAlwaysNullable(boolean alwaysNullable) {
+        return new ForEachCombinator(children, alwaysNullable, nested);
+    }
 }

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/visitor/AggregateFunctionVisitor.java

@@ -322,7 +322,7 @@ default R visitUnionCombinator(UnionCombinator combinator, C context) {
     }
 
     default R visitForEachCombinator(ForEachCombinator combinator, C context) {
-        return visitAggregateFunction(combinator, context);
+        return visitNullableAggregateFunction(combinator, context);
     }
 
     default R visitJavaUdaf(JavaUdaf javaUdaf, C context) {

regression-test/data/function_p0/test_agg_foreach_notnull.out

@@ -1,4 +1,10 @@
 -- This file is automatically generated. You should know what you did if you want to edit this
+-- !select_sum_not_null --
+[1, 2, 3]
+[20]
+[100]
+[null, 2]
+
 -- !sql --
 [1, 2, 3]	[1, 2, 3]	[100, 2, 3]	[100, 2, 3]	[40.333333333333336, 2, 3]	[85.95867768595042, 2, 3]
 

regression-test/suites/function_p0/test_agg_foreach_notnull.groovy

@@ -61,6 +61,10 @@ suite("test_agg_foreach_not_null") {
     (4,[null,2],[[2],null],[null,'c']);
    """
 
+   qt_select_sum_not_null """
+      select sum_foreach(a) from foreach_table_not_null group by id order by id;
+   """
+
    // this case also test combinator should be case-insensitive
    qt_sql """
        select min_ForEach(a), min_by_foreach(a,a),max_foreach(a),max_by_foreach(a,a) , avg_foreach(a),avg_weighted_foreach(a,a) from foreach_table_not_null ;