[Validator] Update validators.zh_CN.xlf, fix translation error

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| License       | MIT
| Doc PR        | 

If you prefer `此字段多余的`, I wuold like to suggest to add `是`, here becomes `此字段是多余的`.
`是` => `be` (here's was) and `多余的` => `not expected`
BTW `多余的` means `superfluous` or `unnecessary` in English, and it's more accurate to use 
`多余的` in Chinese.
Thanks for your suggestion!(谢谢你的建议)