[Bug](agg-state) fix file load insert wrong data to agg_state (#26581)

fix file load insert wrong data to agg_state

fe/fe-core/src/main/java/org/apache/doris/planner/ScanNode.java

@@ -126,7 +126,8 @@ protected Expr castToSlot(SlotDescriptor slotDesc, Expr expr) throws UserExcepti
         if (PrimitiveType.typeWithPrecision.contains(dstType) && PrimitiveType.typeWithPrecision.contains(srcType)
                 && !slotDesc.getType().equals(expr.getType())) {
             return expr.castTo(slotDesc.getType());
-        } else if (dstType != srcType) {
+        } else if (dstType != srcType || slotDesc.getType().isAggStateType() && expr.getType().isAggStateType()
+                && !slotDesc.getType().equals(expr.getType())) {
             return expr.castTo(slotDesc.getType());
         } else {
             return expr;

regression-test/data/mv_p0/dis_26495/dis_26495.out

@@ -0,0 +1,9 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !select --
+1
+
+-- !select --
+1	2	1
+1	3	1
+2	2	2
+

regression-test/data/mv_p0/dis_26495/test.csv

@@ -0,0 +1,3 @@
+1,2
+2,2
+1,3

regression-test/suites/mv_p0/dis_26495/dis_26495.groovy

@@ -0,0 +1,42 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+import org.codehaus.groovy.runtime.IOGroovyMethods
+
+suite ("dis_26495") {
+    sql "set enable_agg_state=true"
+    sql """ DROP TABLE IF EXISTS doris_test; """
+
+    sql """
+        create table doris_test (a int,b int, agg_st_1 agg_state max_by(int ,int))
+            DISTRIBUTED BY HASH(a) BUCKETS 1 properties("replication_num" = "1");
+        """
+
+    sql """insert into doris_test values (1,2,max_by_state(1,2));"""
+
+    streamLoad {
+        table "doris_test"
+        set 'column_separator', ','
+        set 'columns', 'a, b, agg_st_1=max_by_state(a,b)'
+
+        file './test.csv'
+        time 10000 // limit inflight 10s
+    }
+
+    qt_select """select max_by_merge(agg_st_1) from doris_test"""
+    qt_select """select a,b,max_by_merge(agg_st_1) from doris_test group by a,b order by a,b"""
+}