perf(prefetch): enable prefetch for hash join with degree table (risingwavelabs#8566)

Author: soundOfDestiny

src/stream/src/executor/managed_state/join/mod.rs

@@ -365,11 +365,14 @@ impl<K: HashKey, S: StateStore> JoinHashMap<K, S> {
         let mut entry_state = JoinEntryState::default();
 
         if self.need_degree_table {
-            let table_iter_fut = self.state.table.iter_key_and_val(&key, Default::default());
+            let table_iter_fut = self
+                .state
+                .table
+                .iter_key_and_val(&key, PrefetchOptions::new_for_exhaust_iter());
             let degree_table_iter_fut = self
                 .degree_state
                 .table
-                .iter_key_and_val(&key, Default::default());
+                .iter_key_and_val(&key, PrefetchOptions::new_for_exhaust_iter());
 
             let (table_iter, degree_table_iter) =
                 try_join(table_iter_fut, degree_table_iter_fut).await?;