Delete logic to set picture id and tl0 pic idx in encoders.

It would be nice to also delete the fields from CodecSpecificInfo,
but those fields are used on the receive side.

Bug: webrtc:8830
Change-Id: I1a3f13ea2c024cbd73b33fd9dd58e531d3576a55
Reviewed-on: https://webrtc-review.googlesource.com/64780
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22625}

modules/video_coding/video_codec_initializer_unittest.cc

@@ -82,7 +82,7 @@ class VideoCodecInitializerTest : public ::testing::Test {
     if (codec_out_.codecType == VideoCodecType::kVideoCodecVP8) {
       for (int i = 0; i < codec_out_.numberOfSimulcastStreams; ++i) {
         temporal_layers_.emplace_back(
-            TemporalLayers::CreateTemporalLayers(codec_out_, i, 0));
+            TemporalLayers::CreateTemporalLayers(codec_out_, i));
       }
     }
     return true;