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/d3d11va.h

@@ -23,7 +23,6 @@ public:
     virtual void notifyOverlayUpdated(Overlay::OverlayType) override;
     virtual int getRendererAttributes() override;
     virtual int getDecoderCapabilities() override;
-    virtual bool needsTestFrame() override;
     virtual InitFailureReason getInitFailureReason() override;
 
     enum PixelShaders {