[Validator] Fixed string conversion in constraint violations

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10675
| License       | MIT
| Doc PR        | -
I still don't see the usefulness of this return value. It should format the value, i.e. the contents, but it basically returns the same as `formatTypeOf`. It returns the type and not the contents of the array. So it does not add anything new. So ideally it should output a concise representation of the array like `['foo', 1, 'Object(Author)]`. Or at least the array size as I suggested above.

Image the this is used in the `CountValidator`.