executor: fix a batch get executor bug inside a transaction

[tiancaiamao]

What problem does this PR solve?

mysql> create table t (id int primary key auto_increment, name varchar(30));  
Query OK, 0 rows affected (0.01 sec)
mysql> begin; 
Query OK, 0 rows affected (0.00 sec)
mysql> insert into t values (4, 'name'); 
Query OK, 1 row affected (0.01 sec)

mysql> select * from t where id in (4); 
Empty set (0.00 sec)           // This is a bug, should be (4, 'name')!        

mysql> explain select * from t where id in (4);
+-------------------+-------+------+---------------+
| id                | count | task | operator info |
+-------------------+-------+------+---------------+
| Batch_Point_Get_1 | 1.00  | root | table:t       |
+-------------------+-------+------+---------------+
1 row in set (0.00 sec)

What is changed and how it works?

When the BatchGetExec runs inside a transaction, it should consider the data changes
in the membuffer.

Check List

Tests

• Unit test

Release note

• Write release note for bug-fix or new feature.

[codecov]

Codecov Report

Merging #13473 into master will decrease coverage by 0.1457%.
The diff coverage is 83.3333%.

@@               Coverage Diff                @@
##             master     #13473        +/-   ##
================================================
- Coverage   80.3601%   80.2144%   -0.1458%     
================================================
  Files           472        472                
  Lines        114772     114245       -527     
================================================
- Hits          92231      91641       -590     
- Misses        15387      15434        +47     
- Partials       7154       7170        +16

[zimulala]

/run-integration-copr-test

[jackysp]

LGTM

[coocood]

LGTM

[coocood]

/run-all-tests

[sre-bot]

cherry pick to release-3.0 failed

[shenli]

Is this change relative to the bug?

[tiancaiamao]

This change can save many lines of code.