Move a fail point to workers

Fix test_scheduler_leader_change_twice

Signed-off-by: Neil Shen <overvenus@gmail.com>

src/storage/txn/process.rs

@@ -165,7 +165,6 @@ impl Task {
         pool_scheduler: PoolScheduler<SchedContext<E>>,
         scheduler: worker::Scheduler<Msg>,
     ) {
-        fail_point!("scheduler_async_snapshot_finish");
         debug!(
             "receive snapshot finish msg for cid={}, cb_ctx={:?}",
             self.cid, cb_ctx
@@ -218,6 +217,8 @@ impl Task {
         let tag = cmd.tag();
         if readcmd {
             pool_scheduler.schedule(move |ctx: &mut SchedContext<E>| {
+                fail_point!("scheduler_async_snapshot_finish");
+
                 let _processing_read_timer = ctx
                     .processing_read_duration
                     .with_label_values(&[tag])
@@ -228,6 +229,8 @@ impl Task {
             });
         } else {
             pool_scheduler.schedule(move |ctx: &mut SchedContext<E>| {
+                fail_point!("scheduler_async_snapshot_finish");
+
                 let _processing_write_timer = ctx
                     .processing_write_duration
                     .with_label_values(&[tag])