Make sure script cache is created after reimport

[KoBeWi]

Fixes #75684

For whatever reason there are 2 reimport paths. The other one is here:

godot/editor/editor_file_system.cpp

Lines 732 to 736 in c151d32

	scanning = false;
	_update_pending_script_classes();
	emit_signal(SNAME("filesystem_changed"));
	emit_signal(SNAME("sources_changed"), sources_changed.size() > 0);
	first_scan = false;

and it was executed too late. I did not try understand this logic...

[akien-mga]

I'm not able to review all the implications so TIWAGOS, but I think we can give it a spin as it fixes an important bug and seems relatively risk free.

[akien-mga]

Thanks!

[YuriSizov]

Cherry-picked for 4.0.4.