[HttpFoundation] status 201 is allowed to have a body

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | only if someone relied on wrong behavior
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10673
| License       | MIT

Status 201 is allowed to have a response body.