Fix instant power cell drainage (#15927)

Content.Server/PowerCell/PowerCellDrawComponent.cs

@@ -5,11 +5,11 @@ namespace Content.Server.PowerCell;
 /// <summary>
 /// Indicates that the entity's ActivatableUI requires power or else it closes.
 /// </summary>
-[RegisterComponent]
+[RegisterComponent, Access(typeof(PowerCellSystem))]
 public sealed class PowerCellDrawComponent : Component
 {
     [ViewVariables(VVAccess.ReadWrite), DataField("enabled")]
-    public bool Enabled = false;
+    public bool Enabled;
 
     /// <summary>
     /// How much the entity draws while the UI is open.
@@ -23,7 +23,7 @@ public sealed class PowerCellDrawComponent : Component
     /// This is used to ensure the UI won't open again without a minimum use power.
     /// </summary>
     [ViewVariables(VVAccess.ReadWrite), DataField("useRate")]
-    public float UseRate = 0f;
+    public float UseRate;
 
     /// <summary>
     /// When the next automatic power draw will occur