Fix salvage mission biome seed (#20885)

Content.Server/Parallax/BiomeSystem.cs

@@ -107,6 +107,9 @@ public sealed partial class BiomeSystem : SharedBiomeSystem
 
     private void OnBiomeMapInit(EntityUid uid, BiomeComponent component, MapInitEvent args)
     {
+        if (component.Seed != -1)
+            return;
+
         SetSeed(component, _random.Next());
     }
 

Content.Shared/Parallax/Biomes/BiomeComponent.cs

@@ -15,7 +15,7 @@ public sealed partial class BiomeComponent : Component
 
     [ViewVariables(VVAccess.ReadWrite), DataField("seed")]
     [AutoNetworkedField]
-    public int Seed;
+    public int Seed = -1;
 
     /// <summary>
     /// The underlying entity, decal, and tile layers for the biome.