fix(async-io): return coro when __name__ is not present (#2541)

Author: povilasv

Diff for: instrumentation/opentelemetry-instrumentation-asyncio/src/opentelemetry/instrumentation/asyncio/__init__.py

@@ -262,7 +262,7 @@ def trace_item(self, coro_or_future):
 
     async def trace_coroutine(self, coro):
         if not hasattr(coro, "__name__"):
-            return
+            return coro
         start = default_timer()
         attr = {
             "type": "coroutine",