Sometimes simulcast doesn't properly switch encoding

[Rados13]

During work on #134 I met with strange behavior that sometimes even though we peer received callback that encoding switched, the width and height of incoming frames doesn't change. The SSRC in SimulcastTee changes correctly, after a change of encoding. In addition in this situation, WebRTC Stats API doesn't show any qualityLimitationReason.

Example logs from the failed test:

test User disable and then enable medium encoding (TestVideoroom.Integration.SimulcastTest)
     test/integration/simulcast_test.exs:27
     Failed on stage: disable should be encoding: h,
                     receiver stats are: [%{"callbackEncoding" => "m", "framesPerSecond" => 19, "framesReceived" => 356, "height" => 360, "width" => 640}, %{"callbackEncoding" => "m", "framesPerSecond" => 12, "framesReceived" => 389, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 15, "framesReceived" => 404, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 20, "framesReceived" => 441, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 20, "framesReceived" => 481, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 15, "framesReceived" => 519, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 20, "framesReceived" => 559, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 20, "framesReceived" => 595, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 15, "framesReceived" => 632, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 19, "framesReceived" => 674, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 20, "framesReceived" => 710, "height" => 360, "width" => 640}, %{"callbackEncoding" => "h", "framesPerSecond" => 17, "framesReceived" => 747, "height" => 360, "width" => 640}]
                     sender stats are: [%{"h" => %{"framesPerSecond" => 20, "framesSent" => 279, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 279, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 20, "framesSent" => 279, "height" => 360, "qualityLimitationReason" => "none", "width" => 640}}, %{"h" => %{"framesPerSecond" => 20, "framesSent" => 321, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 321, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 19, "framesSent" => 320, "height" => 360, "qualityLimitationReason" => "none", "width" => 640}}, %{"h" => %{"framesPerSecond" => 21, "framesSent" => 362, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 21, "framesSent" => 362, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "height" => 360, "qualityLimitationReason" => "none", "width" => 640}}, %{"h" => %{"framesPerSecond" => 20, "framesSent" => 401, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 401, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "height" => 360, "qualityLimitationReason" => "none", "width" => 640}}, %{"h" => %{"framesPerSecond" => 20, "framesSent" => 442, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 442, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "qualityLimitationReason" => "none"}}, %{"h" => %{"framesPerSecond" => 20, "framesSent" => 482, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 482, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "qualityLimitationReason" => "none"}}, %{"h" => %{"framesPerSecond" => 20, "framesSent" => 522, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 522, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "qualityLimitationReason" => "none"}}, %{"h" => %{"framesPerSecond" => 21, "framesSent" => 563, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 21, "framesSent" => 563, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "qualityLimitationReason" => "none"}}, %{"h" => %{"framesPerSecond" => 20, "framesSent" => 603, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 603, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "qualityLimitationReason" => "none"}}, %{"h" => %{"framesPerSecond" => 21, "framesSent" => 644, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 21, "framesSent" => 644, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "qualityLimitationReason" => "none"}}, %{"h" => %{"framesPerSecond" => 20, "framesSent" => 683, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 683, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "qualityLimitationReason" => "none"}}, %{"h" => %{"framesPerSecond" => 20, "framesSent" => 724, "height" => 720, "qualityLimitationReason" => "none", "width" => 1280}, "l" => %{"framesPerSecond" => 20, "framesSent" => 724, "height" => 180, "qualityLimitationReason" => "none", "width" => 320}, "m" => %{"framesPerSecond" => 0, "framesSent" => 320, "qualityLimitationReason" => "none"}}]