Resolve 'EntitySystem.Get<T>()' is obsolete in content (#27936)

* PROJECT 0 WARNINGS: Resolve `'EntitySystem.Get<T>()' is obsolete` in content

* pass entman

* dog ass test

* webeditor

Content.Server/Maps/Conditions/HolidayMapCondition.cs

@@ -10,7 +10,7 @@ public sealed partial class HolidayMapCondition : GameMapCondition
 
     public override bool Check(GameMapPrototype map)
     {
-        var holidaySystem = EntitySystem.Get<HolidaySystem>();
+        var holidaySystem = IoCManager.Resolve<IEntityManager>().System<HolidaySystem>();
 
         return Holidays.Any(holiday => holidaySystem.IsCurrentlyHoliday(holiday)) ^ Inverted;
     }