Lower the maximum StyleBoxFlat corner detail to 20
Lower the maximum StyleBoxFlat corner detail to 20

This value should be sufficient even for very large corner radii.

This closes #34354.

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