Exception while exporting Span batch.

Describe your environment
Ubuntu 22.04 in Docker
Python 3.11
opentelemetry-api/sdk 1.23.0

Steps to reproduce
I had been running into issues where spans created inside a forked process using multiprocessing.Process were being dropped. Specifically, I was using the wrapt_timeout_decorator library to add timeouts around some sync python code.

After debugging it, I realized that adding some code like:

def exit_gracefully(signum=None, frame=None):
    trace.get_tracer_provider().force_flush()

...

@timeout(1.8, use_signals=False)
def slow_func(self):
  signal.signal(signal.SIGTERM, exit_gracefully)
  try:
    do_stuff()
  finally:
    exit_gracefully()

Got the spans inside do_stuff to be exported successfully most of the time (Though not all of the time).

What is the expected behavior?
No exceptions

What is the actual behavior?
However, after making this change I am running into some exceptions like this sporadically:

Traceback (most recent call last):
  File "/app/lib/python3.11/site-packages/urllib3/connectionpool.py", line 467, in _make_request
    six.raise_from(e, None)
  File "<string>", line 3, in raise_from
  File "/app/lib/python3.11/site-packages/urllib3/connectionpool.py", line 462, in _make_request
    httplib_response = conn.getresponse()
                       ^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/http/client.py", line 1390, in getresponse
    response.begin()
  File "/usr/lib/python3.11/http/client.py", line 325, in begin
    version, status, reason = self._read_status()
                              ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/http/client.py", line 286, in _read_status
    line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/socket.py", line 706, in readinto
    return self._sock.recv_into(b)
           ^^^^^^^^^^^^^^^^^^^^^^^
TimeoutError: timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/app/lib/python3.11/site-packages/requests/adapters.py", line 486, in send
    resp = conn.urlopen(
           ^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/urllib3/connectionpool.py", line 799, in urlopen
    retries = retries.increment(
              ^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/urllib3/util/retry.py", line 550, in increment
    raise six.reraise(type(error), error, _stacktrace)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/urllib3/packages/six.py", line 770, in reraise
    raise value
  File "/app/lib/python3.11/site-packages/urllib3/connectionpool.py", line 715, in urlopen
    httplib_response = self._make_request(
                       ^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/urllib3/connectionpool.py", line 469, in _make_request
    self._raise_timeout(err=e, url=url, timeout_value=read_timeout)
  File "/app/lib/python3.11/site-packages/urllib3/connectionpool.py", line 358, in _raise_timeout
    raise ReadTimeoutError(
urllib3.exceptions.ReadTimeoutError: HTTPConnectionPool(host='0.0.0.0', port=4318): Read timed out. (read timeout=10)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/app/lib/python3.11/site-packages/opentelemetry/sdk/trace/export/__init__.py", line 367, in _export_batch
    self.span_exporter.export(self.spans_list[:idx])  # type: ignore
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/opentelemetry/exporter/otlp/proto/http/trace_exporter/__init__.py", line 145, in export
    resp = self._export(serialized_data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/opentelemetry/exporter/otlp/proto/http/trace_exporter/__init__.py", line 114, in _export
    return self._session.post(
           ^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/requests/sessions.py", line 637, in post
    return self.request("POST", url, data=data, json=json, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/requests/sessions.py", line 589, in request
    resp = self.send(prep, **send_kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/opentelemetry/instrumentation/requests/__init__.py", line 150, in instrumented_send
    return wrapped_send(self, request, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/requests/sessions.py", line 703, in send
    r = adapter.send(request, **kwargs)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/lib/python3.11/site-packages/requests/adapters.py", line 532, in send
    raise ReadTimeout(e, request=request)
requests.exceptions.ReadTimeout: HTTPConnectionPool(host='0.0.0.0', port=4318): Read timed out. (read timeout=10)

Start with opentelemetry/sdk/trace/export/init.py at _export and the OTLP HTTP trace exporter shown in the traceback. Reproduce the multiprocessing.Process and force_flush scenario against the stated Python and OpenTelemetry versions, then determine the expected handling of the exporter timeout. Done should include a regression test and no sporadic exception escaping batch export.