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/drm.cpp

@@ -1353,11 +1353,6 @@ void DrmRenderer::renderFrame(AVFrame* frame)
     drmModeRmFB(m_DrmFd, lastFbId);
 }
 
-bool DrmRenderer::needsTestFrame()
-{
-    return true;
-}
-
 bool DrmRenderer::testRenderFrame(AVFrame* frame) {
     uint32_t fbId;