String: Remove old NO_USE_STDLIB code path
String: Remove old NO_USE_STDLIB code path

We're using the standard library in many core classes by now so
this code path no longer makes sense.

pkowal1982/godot,pkowal1982/godot,firefly2442/godot,vkbsb/godot,BastiaanOlij/godot,vkbsb/godot,josempans/godot,Zylann/godot,Faless/godot,akien-mga/godot,vkbsb/godot,pkowal1982/godot,sanikoyes/godot,vnen/godot,godotengine/godot,guilhermefelipecgs/godot,vnen/godot,guilhermefelipecgs/godot,ZuBsPaCe/godot,sanikoyes/godot,godotengine/godot,Shockblast/godot,pkowal1982/godot,vnen/godot,firefly2442/godot,guilhermefelipecgs/godot,DmitriySalnikov/godot,firefly2442/godot,firefly2442/godot,sanikoyes/godot,Valentactive/godot,Shockblast/godot,ZuBsPaCe/godot,BastiaanOlij/godot,BastiaanOlij/godot,akien-mga/godot,sanikoyes/godot,BastiaanOlij/godot,pkowal1982/godot,vkbsb/godot,BastiaanOlij/godot,akien-mga/godot,Faless/godot,Zylann/godot,BastiaanOlij/godot,Valentactive/godot,Faless/godot,DmitriySalnikov/godot,Valentactive/godot,BastiaanOlij/godot,sanikoyes/godot,vkbsb/godot,sanikoyes/godot,Shockblast/godot,Valentactive/godot,akien-mga/godot,josempans/godot,Zylann/godot,firefly2442/godot,godotengine/godot,Shockblast/godot,akien-mga/godot,vnen/godot,godotengine/godot,akien-mga/godot,josempans/godot,Zylann/godot,vnen/godot,Faless/godot,godotengine/godot,vkbsb/godot,Faless/godot,Zylann/godot,Faless/godot,guilhermefelipecgs/godot,akien-mga/godot,josempans/godot,josempans/godot,DmitriySalnikov/godot,guilhermefelipecgs/godot,ZuBsPaCe/godot,pkowal1982/godot,Zylann/godot,firefly2442/godot,ZuBsPaCe/godot,sanikoyes/godot,ZuBsPaCe/godot,sanikoyes/godot,vkbsb/godot,Faless/godot,Shockblast/godot,firefly2442/godot,vnen/godot,pkowal1982/godot,godotengine/godot,godotengine/godot,josempans/godot,Shockblast/godot,DmitriySalnikov/godot,BastiaanOlij/godot,vnen/godot,guilhermefelipecgs/godot,DmitriySalnikov/godot,DmitriySalnikov/godot,vkbsb/godot,Zylann/godot,josempans/godot,ZuBsPaCe/godot,ZuBsPaCe/godot,pkowal1982/godot,godotengine/godot,Shockblast/godot,Faless/godot,Shockblast/godot,Valentactive/godot,firefly2442/godot,Zylann/godot,guilhermefelipecgs/godot,akien-mga/godot,guilhermefelipecgs/godot,DmitriySalnikov/godot,Valentactive/godot,ZuBsPaCe/godot,josempans/godot,Valentactive/godot,vnen/godot,Valentactive/godot