message: neteq: Add legend in test plot tools
  Add a legend when on the python plots generated with neteq_rtpplay.
  Cr-Commit-Position: refs/heads/main@{#38838}
diff: @@ -284,6 +284,9 @@ void NetEqDelayAnalyzer::CreatePythonScript(
  output << " plt.ylabel('relative delay [ms]')" << std::endl;
  if (!ssrcs_.empty()) {
  auto ssrc_it = ssrcs_.cbegin();
  + output << " plt.legend((\"arrival delay\", \"target delay\", \"playout "
  + "delay\"))"
  + << std::endl;
  output << " plt.title('SSRC: 0x" << std::hex
  << static_cast<int64_t>(*ssrc_it++);
  while (ssrc_it != ssrcs_.end()) {
  