Cookies are duplicated in curl, HTTPie, and HTTP request snippets with latest Spring Framework 5 snapshots

Curl:

```
$ curl 'http://localhost:8080/' -i \
    -H 'Accept: application/json' \
    -H 'Cookie: cookieName=cookieVal' \
    --cookie 'cookieName=cookieVal'
```

HTTPie:

```
$ http GET 'http://localhost:8080/' \
    'Accept:application/json' \
    'Cookie:cookieName=cookieVal' \
    'Cookie:cookieName=cookieVal'
```