Resolve all non-obsoleting warnings in content (#27934)

* Resolve all non-obsoleting warnings in content

* Update ClientGameTicker.cs

* Update SkeletonAccentSystem.cs

* Update BwoinkSystem.cs

Content.Server/IdentityManagement/IdentitySystem.cs

@@ -19,7 +19,7 @@ namespace Content.Server.IdentityManagement;
 /// <summary>
 ///     Responsible for updating the identity of an entity on init or clothing equip/unequip.
 /// </summary>
-public class IdentitySystem : SharedIdentitySystem
+public sealed class IdentitySystem : SharedIdentitySystem
 {
     [Dependency] private readonly IdCardSystem _idCard = default!;
     [Dependency] private readonly IAdminLogManager _adminLog = default!;