[Validator] Update validators.pt_BR.xlf

Fixes for pt_BR validator translations.
As a native speaker, here are the necessary changes to make validators 100% compatible with Brazilian portuguese. =D

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT