hle: kernel: Allocate a dummy KThread for each host thread, and use it for scheduling.

src/yuzu/main.cpp

@@ -1039,8 +1039,6 @@ bool GMainWindow::LoadROM(const QString& filename, std::size_t program_index) {
         std::make_unique<QtWebBrowser>(*this),         // Web Browser
     });
 
-    system.RegisterHostThread();
-
     const Core::System::ResultStatus result{
         system.Load(*render_window, filename.toStdString(), program_index)};