Move tracer output back under `log.V(2)`
Move tracer output back under `log.V(2)`

Respect the logger configuration instead of hard-coding os.Stderr.

cockroachdb/cockroach,petermattis/cockroach,nieyy/cockroach,nieyy/cockroach,nieyy/cockroach,sunya123/cockroach,paperstreet/cockroach,glycerine/cockroach,maxlang/cockroach,cockroachdb/cockroach,cuongdo/cockroach,veteranlu/cockroach,vivekmenezes/cockroach,bg451/cockroach,vivekmenezes/cockroach,petermattis/cockroach,il9ue/cockroach,sunya123/cockroach,glycerine/cockroach,vaibhavarora/cockroach,maxlang/cockroach,veteranlu/cockroach,nieyy/cockroach,il9ue/cockroach,maxlang/cockroach,maxlang/cockroach,paperstreet/cockroach,vivekmenezes/cockroach,sunya123/cockroach,vaibhavarora/cockroach,cuongdo/cockroach,cockroachdb/cockroach,glycerine/cockroach,cuongdo/cockroach,maxlang/cockroach,cockroachdb/cockroach,cuongdo/cockroach,cuongdo/cockroach,nieyy/cockroach,paperstreet/cockroach,glycerine/cockroach,paperstreet/cockroach,cockroachdb/cockroach,il9ue/cockroach,arjun4084346/cockroach,arjun4084346/cockroach,veteranlu/cockroach,veteranlu/cockroach,il9ue/cockroach,glycerine/cockroach,vaibhavarora/cockroach,vaibhavarora/cockroach,glycerine/cockroach,petermattis/cockroach,sunya123/cockroach,bg451/cockroach,arjun4084346/cockroach,arjun4084346/cockroach,petermattis/cockroach,paperstreet/cockroach,cockroachdb/cockroach,nieyy/cockroach,vaibhavarora/cockroach,maxlang/cockroach,nieyy/cockroach,vaibhavarora/cockroach,il9ue/cockroach,petermattis/cockroach,cockroachdb/cockroach,petermattis/cockroach,il9ue/cockroach,bg451/cockroach,arjun4084346/cockroach,vivekmenezes/cockroach,il9ue/cockroach,sunya123/cockroach,vivekmenezes/cockroach,sunya123/cockroach,paperstreet/cockroach,sunya123/cockroach,vaibhavarora/cockroach,arjun4084346/cockroach,sunya123/cockroach,vivekmenezes/cockroach,maxlang/cockroach,bg451/cockroach,paperstreet/cockroach,veteranlu/cockroach,cuongdo/cockroach,veteranlu/cockroach,vivekmenezes/cockroach,glycerine/cockroach,maxlang/cockroach,petermattis/cockroach,cockroachdb/cockroach,veteranlu/cockroach,bg451/cockroach,glycerine/cockroach,cuongdo/cockroach,nieyy/cockroach,il9ue/cockroach,arjun4084346/cockroach,vaibhavarora/cockroach,veteranlu/cockroach,paperstreet/cockroach,vivekmenezes/cockroach,bg451/cockroach,arjun4084346/cockroach,cuongdo/cockroach,petermattis/cockroach,bg451/cockroach