Fix partition selection issue in Azure log processing

Because of the way the goroutine functions close over the loop
variable, every goroutine would likely process the last partition.
Raised by go vet.

Pass the variable as a parameter of the functions.

input/system/azure/logs.go

@@ -135,24 +135,24 @@ func runEventHubHandlers(ctx context.Context, partitionIDs []string, logger *uti
 
 	for _, partitionID := range partitionIDs {
 		wg.Add(1)
-		go func() {
+		go func(partID string) {
 			defer wg.Done()
 
-			partitionClient, err := consumerClient.NewPartitionClient(partitionID, &azeventhubs.PartitionClientOptions{
+			partitionClient, err := consumerClient.NewPartitionClient(partID, &azeventhubs.PartitionClientOptions{
 				StartPosition: azeventhubs.StartPosition{
 					Earliest: to.Ptr(true),
 				},
 			})
 			if err != nil {
-				logger.PrintError("Failed to set up Azure Event Hub partition client for partition %s: %s", partitionID, err)
+				logger.PrintError("Failed to set up Azure Event Hub partition client for partition %s: %s", partID, err)
 			}
 			defer partitionClient.Close(ctx)
 
 			for {
 				events, err := partitionClient.ReceiveEvents(ctx, 1, nil)
 				if err != nil {
 					if err != context.Canceled {
-						logger.PrintError("Failed to receive events from Azure Event Hub for partition %s: %s", partitionID, err)
+						logger.PrintError("Failed to receive events from Azure Event Hub for partition %s: %s", partID, err)
 					}
 					break
 				}
@@ -161,7 +161,7 @@ func runEventHubHandlers(ctx context.Context, partitionIDs []string, logger *uti
 					handler(ctx, event)
 				}
 			}
-		}()
+		}(partitionID)
 	}
 
 	wg.Wait()