weakref version, attempting other branch now

Author: matthewgrossman

instrumentation/opentelemetry-instrumentation-flask/src/opentelemetry/instrumentation/flask/__init__.py

@@ -405,7 +405,6 @@ def _before_request():
 
         activation = trace.use_span(span, end_on_exit=True)
         activation.__enter__()  # pylint: disable=E1101
-
         flask_request_environ[_ENVIRON_ACTIVATION_KEY] = activation
         flask_request_environ[_ENVIRON_REQCTX_REF_KEY] = _request_ctx_ref()
         flask_request_environ[_ENVIRON_SPAN_KEY] = span