network: FairQueueTrafficPolicing→FairQueueing

This never made into a release, so we can change the name with impunity.
Suggested by Davide Pesavento.

I opted to add the "ing" ending. "Fair queuing" is the name of the general
concept and algorithm, and "Fair queue" is mostly used for the implementation
name.

test/fuzz/fuzz-network-parser/directives.network

@@ -299,7 +299,7 @@ TargetSec=
 IntervalSec=
 CEThresholdSec=
 ECN=
-[FairQueueTrafficPolicing]
+[FairQueueing]
 Parent=
 PacketLimit=
 FlowLimit=