APM: Use compressor.Encoding() for error log messages (#29207)

pkg/trace/writer/trace.go

@@ -294,14 +294,14 @@ func (w *TraceWriter) serialize(pl *pb.AgentPayload) {
 	if err != nil {
 		// it will never happen, unless an invalid compression is chosen;
 		// we know gzip.BestSpeed is valid.
-		log.Errorf("Failed to initialize gzip writer. No traces can be sent: %v", err)
+		log.Errorf("Failed to initialize %s writer. No traces can be sent: %v", w.compressor.Encoding(), err)
 		return
 	}
 	if _, err := writer.Write(b); err != nil {
-		log.Errorf("Error gzipping trace payload: %v", err)
+		log.Errorf("Error %s trace payload: %v", w.compressor.Encoding(), err)
 	}
 	if err := writer.Close(); err != nil {
-		log.Errorf("Error closing gzip stream when writing trace payload: %v", err)
+		log.Errorf("Error closing %s stream when writing trace payload: %v", w.compressor.Encoding(), err)
 	}
 	sendPayloads(w.senders, p, w.syncMode)