[fix](datetime) fix datetime round on BE (apache#31205) (apache#31229)

with tmp as (
            select CONCAT(
                YEAR('2024-02-06 03:37:07.157'), '-', 
                LPAD(MONTH('2024-02-06 03:37:07.157'), 2, '0'), '-',
                LPAD(DAY('2024-02-06 03:37:07.157'), 2, '0'), ' ',
                LPAD(HOUR('2024-02-06 03:37:07.157'), 2, '0'), ':',
                LPAD(MINUTE('2024-02-06 03:37:07.157'), 2, '0'), ':',
                LPAD(SECOND('2024-02-06 03:37:07.157'), 2, '0'), '.', "123456789" )
            AS generated_string)
            select generated_string, cast(generated_string as DateTime(6)) from tmp
before (incorrect round)

+-------------------------------+-----------------------------------------+
| generated_string              | cast(generated_string as DATETIMEV2(6)) |
+-------------------------------+-----------------------------------------+
| 2024-02-06 03:37:07.123456789 | 2024-02-06 03:37:07.123456              |
+-------------------------------+-----------------------------------------+
after (round up, keep consistent with mysql):

+-------------------------------+-----------------------------------------+
| generated_string              | cast(generated_string as DATETIMEV2(6)) |
+-------------------------------+-----------------------------------------+
| 2024-02-06 03:37:07.123456789 | 2024-02-06 03:37:07.123457              |
+-------------------------------+-----------------------------------------+
1 row in set (0.03 sec)
same work with apache#30744 but implemented on BE

be/src/vec/runtime/vdatetime_value.cpp

@@ -2037,8 +2037,8 @@ bool DateV2Value<T>::from_date_str_base(const char* date_str, int len, int scale
             temp_val *= int_exp10(std::max(0L, 6 - ms_part));
             if constexpr (is_datetime) {
                 if (scale >= 0) {
-                    if (scale == 6 && ms_part > 6) {
-                        if (ptr < end && isdigit(*ptr) && *ptr >= '5') {
+                    if (scale == 6 && ms_part >= 6) {
+                        if (ptr <= end && isdigit(*ptr) && *ptr >= '5') {
                             temp_val += 1;
                         }
                     } else {

regression-test/data/datatype_p0/datetimev2/test_round.out

@@ -0,0 +1,11 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !cast --
+2024-02-06 03:37:07.123456789	2024-02-06T03:37:07.123457
+
+-- !cast --
+1	2024-02-01 12:13:14.123456	2024-02-01T12:13:14.123456
+2	2024-02-01 12:13:14.1234567	2024-02-01T12:13:14.123457
+3	2024-02-01 12:13:14.12345671	2024-02-01T12:13:14.123457
+4	2024-02-01 12:13:14.1234561	2024-02-01T12:13:14.123456
+5	2024-02-01 12:13:14.12345615	2024-02-01T12:13:14.123456
+

regression-test/suites/datatype_p0/datetimev2/test_round.groovy

@@ -0,0 +1,58 @@
+// 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.
+
+suite("test_time_round") {
+    qt_cast """
+        with tmp as (
+            select CONCAT(
+                YEAR('2024-02-06 03:37:07.157'), '-',
+                LPAD(MONTH('2024-02-06 03:37:07.157'), 2, '0'), '-',
+                LPAD(DAY('2024-02-06 03:37:07.157'), 2, '0'), ' ',
+                LPAD(HOUR('2024-02-06 03:37:07.157'), 2, '0'), ':',
+                LPAD(MINUTE('2024-02-06 03:37:07.157'), 2, '0'), ':',
+                LPAD(SECOND('2024-02-06 03:37:07.157'), 2, '0'), '.', "123456789")
+            AS generated_string)
+            select generated_string, cast(generated_string as DateTime(6)) from tmp
+    """
+    sql """
+        DROP TABLE IF EXISTS test_time_round;
+    """
+    sql """
+        CREATE TABLE test_time_round (`rowid` int, str varchar)
+        ENGINE=OLAP
+        UNIQUE KEY(`rowid`)
+        COMMENT "OLAP"
+        DISTRIBUTED BY HASH(`rowid`) BUCKETS 3
+        PROPERTIES (
+            "replication_num" = "1",
+            "colocate_with" = "lineitem_orders",
+            "enable_unique_key_merge_on_write" = "true"
+        );
+    """
+    sql """
+        insert into test_time_round values
+            (1, "2024-02-01 12:13:14.123456"),
+            (2, "2024-02-01 12:13:14.1234567"),
+            (3, "2024-02-01 12:13:14.12345671"),
+            (4, "2024-02-01 12:13:14.1234561"),
+            (5, "2024-02-01 12:13:14.12345615")
+    """
+
+    qt_cast """
+        select *, cast (str as Datetime(6)) from test_time_round order by rowid;
+    """
+}