refactor: clarify comments for proof task handles in MultiproofManager

- Updated comments for `proof_task_handle` parameters in the `MultiproofManager` initialization to specify their roles for storage and account proof workers, improving code clarity and maintainability.

crates/engine/tree/src/tree/payload_processor/multiproof.rs

@@ -728,8 +728,8 @@ where
             multiproof_manager: MultiproofManager::new(
                 executor,
                 metrics.clone(),
-                proof_task_handle.clone(),
-                proof_task_handle,
+                proof_task_handle.clone(), // handle for storage proof workers
+                proof_task_handle,         // handle for account proof workers
                 max_concurrency,
             ),
             metrics,