SCons: Fix MSVC D9025 warning overriding opt level
SCons: Fix MSVC D9025 warning overriding opt level

And cleanup disable_warnings too to avoid setting `/w` / `-w` multiple times.

vkbsb/godot,godotengine/godot,pkowal1982/godot,BastiaanOlij/godot,BastiaanOlij/godot,josempans/godot,guilhermefelipecgs/godot,pkowal1982/godot,vkbsb/godot,BastiaanOlij/godot,josempans/godot,josempans/godot,vkbsb/godot,guilhermefelipecgs/godot,godotengine/godot,guilhermefelipecgs/godot,godotengine/godot,sanikoyes/godot,BastiaanOlij/godot,pkowal1982/godot,guilhermefelipecgs/godot,josempans/godot,josempans/godot,pkowal1982/godot,BastiaanOlij/godot,guilhermefelipecgs/godot,sanikoyes/godot,BastiaanOlij/godot,josempans/godot,pkowal1982/godot,sanikoyes/godot,pkowal1982/godot,godotengine/godot,guilhermefelipecgs/godot,sanikoyes/godot,josempans/godot,vkbsb/godot,godotengine/godot,vkbsb/godot,vkbsb/godot,sanikoyes/godot,godotengine/godot,guilhermefelipecgs/godot,sanikoyes/godot,sanikoyes/godot,BastiaanOlij/godot,guilhermefelipecgs/godot,josempans/godot,godotengine/godot,godotengine/godot,vkbsb/godot,vkbsb/godot,BastiaanOlij/godot,pkowal1982/godot,pkowal1982/godot,sanikoyes/godot