Retry on HTTP 200 with empty response body

[emanuelsdsj]

Description

fixed #596

TrinoRequest.process() calls json.loads(http_response.text)
immediately after checking http_response.ok. When Trino returns
HTTP 200 with an empty body under load, this raises a bare
JSONDecodeError that is not in the handled_exceptions list of
_retry_with, so no retry is attempted and the exception
propagates unhandled to the caller.

Two changes to address this:

• Add a retry condition in max_attempts.setter for HTTP 200
  responses with an empty body, so the existing exponential
  backoff mechanism retries them — consistent with how 429/502/
  503/504 are already handled.
• Add a guard in process() that raises TrinoConnectionError
  with a descriptive message if an empty body reaches that point
  (e.g. after retries are exhausted), instead of leaking a raw
  JSONDecodeError.

Non-technical explanation

When the server returned an empty response under load, the client
crashed with an unhelpful JSONDecodeError. It now retries
automatically and, if retries are exhausted, raises a clear error
message.

Release notes

( ) This is not user-visible or docs only and no release notes are required.
( ) Release notes are required, please propose a release note for me.
(x) Release notes are required, with the following suggested text:

* Fix client crash with `JSONDecodeError` on HTTP 200 with empty
  response body by retrying the request. ({issue}`596`)

[emanuelsdsj]

I believe that both failures are related to the installation of dependencies, even before any tests were run.