EntityLookup as a system for content (#6931)

Content.Server/Radiation/RadiationPulseSystem.cs

@@ -13,7 +13,7 @@ namespace Content.Server.Radiation
     public sealed class RadiationPulseSystem : EntitySystem
     {
         [Dependency] private readonly IEntityManager _entMan = default!;
-        [Dependency] private readonly IEntityLookup _lookup = default!;
+        [Dependency] private readonly EntityLookupSystem _lookup = default!;
 
         private const float RadiationCooldown = 1.0f;
         private float _accumulator;