Revert "Refactor Damage to use Protoypes (#4262)"

This reverts commit 20bf5739a9.

Content.Shared/Damage/DamageTypePrototype.cs

@@ -1,18 +0,0 @@
-using System;
-using Robust.Shared.Prototypes;
-using Robust.Shared.Serialization;
-using Robust.Shared.Serialization.Manager.Attributes;
-
-namespace Content.Shared.Damage
-{
-    /// <summary>
-    ///     A single damage type. These types are grouped together in <see cref="DamageGroupPrototype"/>s. 
-    /// </summary>
-    [Prototype("damageType")]
-    [Serializable, NetSerializable]
-    public class DamageTypePrototype : IPrototype
-    {
-        [DataField("id", required: true)]
-        public string ID { get; } = default!;
-    }
-}