regular expression: some incorrect codegen

See https://github.com/oxc-project/oxc/pull/6411

```
Expect to Parse: tasks/coverage/test262/test/built-ins/String/prototype/split/separator-regexp.js

  × Regular Expression content mismatch for `/\cY/`: `\c` == `\c`
```