Removes spammy SDP log

Example of current output in appr.tc:

https://paste.googleplex.com/4582802164023296

No-Try: True
Bug: None
Change-Id: I9b717b9c13e771e84682d9e3d3ee6b0920a85a44
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/196526
Commit-Queue: Henrik Andreassson <henrika@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32796}

pc/webrtc_sdp.cc

@@ -3073,7 +3073,7 @@ bool ParseContent(const std::string& message,
 
     if (!IsLineType(line, kLineTypeAttributes)) {
       // TODO(deadbeef): Handle other lines if needed.
-      RTC_LOG(LS_INFO) << "Ignored line: " << line;
+      RTC_LOG(LS_VERBOSE) << "Ignored line: " << line;
       continue;
     }