Preserve metric type when using filters in output plugins (#4481)

internal/models/running_output.go

@@ -105,12 +105,13 @@ func (ro *RunningOutput) AddMetric(m telegraf.Metric) {
 		tags := m.Tags()
 		fields := m.Fields()
 		t := m.Time()
+		tp := m.Type()
 		if ok := ro.Config.Filter.Apply(name, fields, tags); !ok {
 			ro.MetricsFiltered.Incr(1)
 			return
 		}
 		// error is not possible if creating from another metric, so ignore.
-		m, _ = metric.New(name, tags, fields, t)
+		m, _ = metric.New(name, tags, fields, t, tp)
 	}
 
 	ro.metrics.Add(m)