Disable V-Sync when running benchmarks

This is required for accurate CPU/GPU time reporting, as the GPU
may downclock if it ends up being underutilized due to the FPS cap
imposed by V-Sync (leading to artificially increased CPU/GPU times).

project.godot

@@ -28,6 +28,7 @@ gdscript/warnings/standalone_expression=0
 window/size/viewport_width=1920
 window/size/viewport_height=1080
 window/stretch/mode="viewport"
+window/vsync/vsync_mode=0
 
 [dotnet]