Revert to calculate network stream and filtered bandwidth averages without relay types

In #40059 (closed) we started to calculate those averages by relay type, but turned out it is not what Torflow is doing, because in this line: https://gitweb.torproject.org/torflow.git/tree/NetworkScanners/BwAuthority/aggregate.py#n536, it assigns back to each relay type the averages for all the network.