qt: increase waiting time in `CompositorDirectComposition::setupVoutWindow()`

When m_setupStateCond.wait() is called, the scene graph has already started to initialize itself. So, 2.5 seconds waiting time was considered to be fair.

2.5 seconds were enough for Nvidia and VirtualBox drivers. However, it turns out that AMD needs more time. It was reported that 3 seconds is enough, however 5 seconds should be better just to be safe.

This is mainly relevant when the application starts with a video. If 5 seconds is not enough, then the video should still start, albeit in a separate window.

Request review @chub.