Lint more const string prototypes (#18922)

Content.Server/Spreader/KudzuSystem.cs

@@ -12,6 +12,7 @@ public sealed class KudzuSystem : EntitySystem
     [Dependency] private readonly SharedAppearanceSystem _appearance = default!;
     [Dependency] private readonly DamageableSystem _damageable = default!;
 
+    [ValidatePrototypeId<EdgeSpreaderPrototype>]
     private const string KudzuGroup = "kudzu";
 
     /// <inheritdoc/>

Content.Server/Spreader/SpreaderSystem.cs

@@ -31,6 +31,7 @@ public sealed class SpreaderSystem : EntitySystem
 
     private readonly List<string> _spreaderGroups = new();
 
+    [ValidatePrototypeId<TagPrototype>]
     private const string IgnoredTag = "SpreaderIgnore";
 
     /// <inheritdoc/>