[NTOFNEWDAQ-720] Fix FileList hanging on firefox
Problem was: In rpc mode there is an automating polling every 1 second. For big runs with a lot of file, the "MERGER/Files" rpc service needs more than 1 sec to get the data so on the next polling the worker was reset.
Solution: Now I've implemented a simple throttle mechanism that ignore new polling request until we get an answer from the RPC service.