Ore tweaks (#16930)

- Guaranteed spawns in salvage
- Triple vein count
- Made it so rocks only drop 1 as it's kinda whacky (I believe they still convert differently to bars).

Content.Shared/Procedural/Loot/SalvageLootPrototype.cs

@@ -12,6 +12,11 @@ public sealed class SalvageLootPrototype : IPrototype
 {
     [IdDataField] public string ID { get; } = default!;
 
+    /// <summary>
+    /// Should this loot always spawn if possible. Used for stuff such as ore.
+    /// </summary>
+    [DataField("guaranteed")] public bool Guaranteed;
+
     [DataField("desc")] public string Description = string.Empty;
 
     /// <summary>