[HttpFoundation] Remove content-related headers if content is empty
bug #11244 [HttpFoundation] Remove body-related headers when sending the response, if body is empty (SimonSimCity)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #11244).

Discussion
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[HttpFoundation] Remove body-related headers when sending the response, if body is empty

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

I've updated the implementation for informational and 204 or 304 responses. They will now, as they have no content, not return headers like `content-type` or `content-length`.

I'm unsure about `content-length` - we could also set it hardcoded to zero ... but I thought, that (because the specs say that it just can't have a response-body) the system should not return anything here.

Commits
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9dbe89d [HttpFoundation] Remove content-related headers if content is empty