net: remove SetMaxOutboundTimeframe

This was introduced in 872fee3fcc and it's unclear
if it's ever been used.

src/net.cpp

@@ -2885,18 +2885,6 @@ uint64_t CConnman::GetMaxOutboundTimeLeftInCycle()
     return (cycleEndTime < now) ? 0 : cycleEndTime - GetTime();
 }
 
-void CConnman::SetMaxOutboundTimeframe(uint64_t timeframe)
-{
-    LOCK(cs_totalBytesSent);
-    if (nMaxOutboundTimeframe != timeframe)
-    {
-        // reset measure-cycle in case of changing
-        // the timeframe
-        nMaxOutboundCycleStartTime = GetTime();
-    }
-    nMaxOutboundTimeframe = timeframe;
-}
-
 bool CConnman::OutboundTargetReached(bool historicalBlockServingLimit)
 {
     LOCK(cs_totalBytesSent);