Test all renderers before use

Every renderer except SDL had opted-in for testing due to various
quirks discovered over the years, so just do away with this option
and test all renderers.

app/streaming/video/ffmpeg-renderers/vaapi.cpp

@@ -574,14 +574,6 @@ VAAPIRenderer::prepareDecoderContext(AVCodecContext* context, AVDictionary**)
     return true;
 }
 
-bool
-VAAPIRenderer::needsTestFrame()
-{
-    // We need a test frame to see if this VAAPI driver
-    // supports the profile used for streaming
-    return true;
-}
-
 bool
 VAAPIRenderer::isDirectRenderingSupported()
 {