Incomplete Suppression of Transfer-Encoding: chunked Header in HTTP/2 After Redirect From HTTP/1.1

When curl send a request with `Transfer-Encoding: chunked` using HTTP/1.1, and follows a redirect to an HTTP/2 endpoint, the `upload_chunky` flag is not properly reset. As a result, the `Transfer-Encoding: chunked` header is sent in the subsequent request even when HTTP/2 is negotiated/used.

curl -vvv --http1.1 --no-alpn -L --http2 -k \
  -H "Transfer-Encoding: chunked" \
  -H "Content-Type: text/plain" \
  -d "This is chunked encoding bug test data" \
  http://test.local:8080/