[core] catch exception in async_callback (#46488) (#46519)

backport.
fix
`python/ray/tests/test_asyncio.py::test_on_completed_callback_refcount[True]`

Signed-off-by: hongchaodeng <hongchaodeng1@gmail.com>

python/ray/_raylet.pyx

@@ -5154,6 +5154,10 @@ cdef void async_callback(shared_ptr[CRayObject] obj,
 
         user_callback = <object>user_callback_ptr
         user_callback(result)
+    except Exception:
+        # Only log the error here because this calllback is called from Cpp
+        # and Cython will ignore the exception anyway
+        logger.exception(f"failed to run async callback (user func)")
     finally:
         # NOTE: we manually increment the Python reference count of the callback when
         # registering it in the core worker, so we must decrement here to avoid a leak.