Remove "Missing track ID" StatsCollector log message

Bug: None
Change-Id: I94a70d5cbe4238220bf0939ba5807cf51195fe7f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/147661
Reviewed-by: Amit Hilbuch <amithi@webrtc.org>
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28727}

pc/stats_collector.cc

@@ -393,9 +393,6 @@ std::string GetTrackIdBySsrc(
       return it->second;
     }
   }
-  RTC_LOG(LS_INFO) << "Missing track ID for "
-                   << (direction == StatsReport::kSend ? "send" : "recv")
-                   << " SSRC=" << ssrc << ".";
   return "";
 }