Revert "Gamerule Entities" (#15724)

Content.Server/GameTicking/Rules/Configurations/GameRuleConfiguration.cs

@@ -0,0 +1,13 @@
+namespace Content.Server.GameTicking.Rules.Configurations;
+
+/// <summary>
+/// Configures a game rule, providing information like what maps to use or how long to run.
+/// </summary>
+[ImplicitDataDefinitionForInheritors]
+public abstract class GameRuleConfiguration
+{
+    /// <summary>
+    /// The game rule this configuration is intended for.
+    /// </summary>
+    public abstract string Id { get; }
+}