Fix dead people standing up after being stunned (#3330)

* fix crit/dead players standing up

* actually fix crit/dead players standing up

* nullable + missed check

Co-authored-by: cyclowns <cyclowns@protonmail.ch>

Content.Server/GameObjects/Components/Buckle/BuckleComponent.cs

@@ -337,7 +337,8 @@ namespace Content.Server.GameObjects.Components.Buckle
 
             Appearance?.SetData(BuckleVisuals.Buckled, false);
 
-            if (_stunnable != null && _stunnable.KnockedDown)
+            if (_stunnable != null && _stunnable.KnockedDown
+                || (_mobState?.IsIncapacitated() ?? false))
             {
                 EntitySystem.Get<StandingStateSystem>().Down(Owner);
             }