Change many metal nodes to use default metal sounds

mods/stairs/init.lua

@@ -473,7 +473,7 @@ stairs.register_stair_and_slab(
 	{"default_steel_block.png"},
 	"Steel Block Stair",
 	"Steel Block Slab",
-	default.node_sound_stone_defaults()
+	default.node_sound_metal_defaults()
 )
 
 stairs.register_stair_and_slab(
@@ -483,7 +483,7 @@ stairs.register_stair_and_slab(
 	{"default_copper_block.png"},
 	"Copper Block Stair",
 	"Copper Block Slab",
-	default.node_sound_stone_defaults()
+	default.node_sound_metal_defaults()
 )
 
 stairs.register_stair_and_slab(
@@ -493,7 +493,7 @@ stairs.register_stair_and_slab(
 	{"default_bronze_block.png"},
 	"Bronze Block Stair",
 	"Bronze Block Slab",
-	default.node_sound_stone_defaults()
+	default.node_sound_metal_defaults()
 )
 
 stairs.register_stair_and_slab(
@@ -503,5 +503,5 @@ stairs.register_stair_and_slab(
 	{"default_gold_block.png"},
 	"Gold Block Stair",
 	"Gold Block Slab",
-	default.node_sound_stone_defaults()
+	default.node_sound_metal_defaults()
 )