Investigate `--import` flag for CI steps

[rsubtil]

godotengine/godot#90431 adds a new CLI flag to ensure Godot imports the project before attempting to export it. This is needed as otherwise a lot of script/asset errors occur, and the final build is broken.

However, this would imply having to compile a custom editor build just to take advantage of it. For now we are using the timeout hack, but when this makes into a public build, we can switch to the new version.

[rsubtil]

Also would be a good idea to check if this import step is indeed the root cause of #245.