decodebin3: do not remove elements if receive EOS from all tracks
requested to merge elliot_chen/gstreamer:decodebin3-do-not-remove-elements-if-receive-EOS-from-all-tracks into main
In some cases, maybe both video and audio track send EOS in trick mode while the play has no finished. And It will cause failure if play switch to normal playback due to remove elements if receive EOS from all tracks.