When a non TLS connection attempts to connect and send data to a Redpanda
TLS enabled endpoint, OpenSSL may report different error codes depending on
what it sees on the incoming packet:

* `ERROR_WRONG_VERSION_NUMBER` - reported when OpenSSL inspects the packet
  expecting to see a known TLS version but the one it sees is unknown.
  This is distinct to seeing an unsupported version.
* `ERROR_HTTP_REQUEST` - similar to `ERROR_WRONG_VERSION_NUMBER`, however in
  this situation, the packet starts with a known HTTP verb (e.g. `GET`, or
  `POST`, etc).
* `ERROR_HTTPS_PROXY_REQUEST` - like `ERROR_HTTP_REQUEST`, however the
  packet starts with `CONNE`

Signed-off-by: Michael Boquard <michael@redpanda.com>
(cherry picked from commit 0803e0d)