[Derivation Pipeline] Long waiting to be sheduled time of derivation-pipeline worker loop future

[yiweichi]

By checking the tokio-console dashboard of RN, we spotted an unexpected behavior of the future derivation-pipeline worker. Normal future should have very short sched time(waiting for the tokio runtime to execute it) and long Idle time, whereas the the future derivation-pipeline worker has a very long sched time but short Idle time, which means the future is starved to be executed.

   Warn  ID    State  Name  Total  Busy   Sched  Idle   Polls Kind     Location                                                                                             Fields-                                                                                        
   ! 1      80 IDLE         10m43s  173ms 10m29s    13s 294   task     /app/crates/derivation-pipeline/src/lib.rs:153:9                                                     size.bytes=632 target=tokio::task                            

We better check the rationale of this behavior.