[Revert] Reverts Ninja (#15516)

* Revert "[Antag] add space ninja as midround antag (#14069)"

This reverts commit c1cda0dbf8.

* Revert "[Fix] move ninja objectives into NinjaRole (#15490)"

This reverts commit 251f429fb3.

Content.Server/Explosion/Components/AutomatedTimerComponent.cs

@@ -1,9 +0,0 @@
-namespace Content.Server.Explosion.Components;
-
-/// <summary>
-///     Disallows starting the timer by hand, must be stuck or triggered by a system.
-/// </summary>
-[RegisterComponent]
-public sealed class AutomatedTimerComponent : Component
-{
-}