fix: Only show accrued traffic charges and estimated overages for the current month (#9440)

For past months, customers can refer to their invoices instead. Hiding
it when the selection is not the current month avoids weird things such
as estimation errors due to to a month not having finished (vs what it
actually *was* when it finished), potential changes in traffic package
pricing, etc.

frontend/src/component/admin/network/NetworkTrafficUsage/NetworkTrafficUsage.tsx

@@ -57,6 +57,7 @@ const NetworkTrafficUsage: FC = () => {
 
     const showOverageCalculations =
         chartDataSelection.grouping === 'daily' &&
+        chartDataSelection.month === currentMonth &&
         includedTraffic > 0 &&
         usageTotal - includedTraffic > 0 &&
         estimateTrafficDataCost;