fix(inputs.tail): Prevent deadlock when closing and max undelivered lines hit (#15649)

plugins/inputs/tail/tail.go

@@ -370,6 +370,11 @@ func (t *Tail) receiver(parser telegraf.Parser, tailer *tail.Tail) {
 		select {
 		case <-t.ctx.Done():
 			return
+		// Tail is trying to close so drain the sem to allow the receiver
+		// to exit. This condition is hit when the tailer may have hit the
+		// maximum undelivered lines and is trying to close.
+		case <-tailer.Dying():
+			<-t.sem
 		case t.sem <- empty{}:
 			t.acc.AddTrackingMetricGroup(metrics)
 		}