The result of comparison between cast VARBINARY to binary and binary is not correct

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t(a varbinary(10),b binary(10));
insert into t values(31,31);
select a,b,cast(a as binary(10))=b from t; 

2. What did you expect to see? (Required)

+------------+------------------------+-------------------------+
| a          | b                      | cast(a as binary(10))=b |
+------------+------------------------+-------------------------+
| 0x3331     | 0x33310000000000000000 |                       1 |
+------------+------------------------+-------------------------+

3. What did you see instead (Required)

+------------+------------------------+-------------------------+
| a          | b                      | cast(a as binary(10))=b |
+------------+------------------------+-------------------------+
| 0x3331     | 0x33310000000000000000 |                       0 |
+------------+------------------------+-------------------------+

4. What is your TiFlash version? (Required)

Release Version: v6.1.0-nightly
Edition: Community
Git Commit Hash: 32b9c14779c2a7dd73003667d81bb42f67a33385
Git Branch: heads/refs/tags/v6.1.0-nightly
UTC Build Time: 2022-04-11 11:02:23
GoVersion: go1.18
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false

Start by running the supplied CREATE TABLE, INSERT, and SELECT reproduction against TiFlash and compare the result with the expected output. Trace the handling of VARBINARY-to-BINARY casts and binary equality, then add a regression test for this query. Done means the comparison returns 1 while preserving the shown binary values.