TiKV crashes

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

```sql
/* init */ DROP TABLE IF EXISTS t;
/* init */ CREATE TABLE t (c1 BIT (30));
/* init */ INSERT INTO t VALUES (b'100001001101010001000010001111');
/* init */ INSERT INTO t VALUES (b'010010001100110110000011010101');

UPDATE t SET c1 = b'111001111010010110110010001011' WHERE c1 NOT LIKE c1;
```

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

The UPADTE statement executes successfully, and no rows in table t are updated.

### 3. What did you see instead (Required)

TiKV crashes.

The UPDATE statement does not receive any execution feedback.

In the TiKV log, the error message is roughly as follows:

```bash
[FATAL] [lib.rs:481] ["range end index 2 out of range for slice of length 1"]
```

By the way, executing the following UPDATE statement will not cause TiKV to crash.

```sql
UPDATE t SET c1 = b'111001111010010110110010001011' WHERE FALSE;
```

And executing the following test case (with a reduced bit length) will also not cause TiKV to crash.

```sql
/* init */ DROP TABLE IF EXISTS t;
/* init */ CREATE TABLE t (c1 BIT (20));
/* init */ INSERT INTO t VALUES (b'10000100110101000100');
/* init */ INSERT INTO t VALUES (b'01001000110011011000');

UPDATE t SET c1 = b'11100111101001011011' WHERE c1 NOT LIKE c1;
```

### 4. What is your TiDB version? (Required)

```sql
mysql> select version();
+--------------------+
| version() |
+--------------------+
| 8.0.11-TiDB-v8.5.3 |
+--------------------+
```

```sql
mysql> select tidb_version();
+-----------------------------------------------------------+
| tidb_version() |
+-----------------------------------------------------------+
| Release Version: v8.5.3 |
| Edition: Community |
| Git Commit Hash: dc2548aac79a712265e831cff2a3a896bc0a5a38 |
| Git Branch: HEAD |
| UTC Build Time: 2025-07-31 13:54:43 |
| GoVersion: go1.23.8 |
| Race Enabled: false |
| Check Table Before Drop: false |
| Store: tikv |
+-----------------------------------------------------------+
```