middleware: fix waitForLeader in redirector panic (#8407)

close #8406

Signed-off-by: husharp <[email protected]>

pkg/utils/apiutil/serverapi/middleware.go

@@ -270,7 +270,7 @@ func (h *redirector) waitForLeader(r *http.Request) (leader *pdpb.Member) {
 			}
 		case <-r.Context().Done():
 			return
-		case <-h.s.LoopContext().Done():
+		case <-h.s.Context().Done():
 			return
 		}
 	}