Improper status code handling between flask and wsgi instrumentation: bare status codes.

Flask's Response type status field can be just a simple string or an integer but the wsgi instrumentation here expects it to be able to be split on a string (understandable as that's wsgi / pep 3333 compliant).

This line https://github.com/open-telemetry/opentelemetry-python-contrib/blob/753e22896a11cadf28c4f64acdfcfd73350d7d90/instrumentation/opentelemetry-instrumentation-flask/src/opentelemetry/instrumentation/flask/__init__.py#L107-L110

Can blow up in this manner:

  File "/usr/local/lib/python/dist-packages/flask/app.py", line 2453, in wsgi_app
    return response(environ, start_response)
  File "/usr/local/lib/python/dist-packages/werkzeug/wrappers/base_response.py", line 701, in __call__
    start_response(status, headers)
  File "/usr/local/lib/python/dist-packages/opentelemetry/instrumentation/flask/__init__.py", line 109, in _start_response
    span, status, response_headers
  File "/usr/local/lib/python/dist-packages/opentelemetry/instrumentation/wsgi/__init__.py", line 163, in add_response_attributes
    status_code, _ = start_response_status.split(" ", 1)
ValueError: not enough values to unpack (expected 2, got 1)

Read instrumentation/opentelemetry-instrumentation-flask/src/opentelemetry/instrumentation/flask/init.py around lines 107-110 and the WSGI add_response_attributes entry point. Reproduce the failure with a Flask response using a bare status string or integer, then verify instrumentation handles it without the split error while preserving response status attributes.