[Java] Release actor instance reference when Ray.exitActor() is invoked (#11324)

python/ray/includes/libcoreworker.pxd

@@ -19,6 +19,7 @@ from ray.includes.unique_ids cimport (
     CTaskID,
     CObjectID,
     CPlacementGroupID,
+    CWorkerID,
 )
 from ray.includes.common cimport (
     CAddress,
@@ -227,6 +228,7 @@ cdef extern from "ray/core_worker/core_worker.h" nogil:
             const c_vector[CObjectID] &return_ids,
             c_vector[shared_ptr[CRayObject]] *returns) nogil
          ) task_execution_callback
+        (void(const CWorkerID &) nogil) on_worker_shutdown
         (CRayStatus() nogil) check_signals
         (void() nogil) gc_collect
         (c_vector[c_string](const c_vector[CObjectID]&) nogil) spill_objects