Fix content.integration tests warnings (#17817)

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.IntegrationTests/Tests/Chemistry/DispenserTest.cs

@@ -1,9 +1,7 @@
-using System.Threading.Tasks;
 using Content.Client.Chemistry.UI;
 using Content.IntegrationTests.Tests.Interaction;
 using Content.Shared.Chemistry;
 using Content.Shared.Containers.ItemSlots;
-using NUnit.Framework;
 
 namespace Content.IntegrationTests.Tests.Chemistry;
 
@@ -20,7 +18,7 @@ public sealed class DispenserTest : InteractionTest
 
         // Insert beaker
         await Interact("Beaker");
-        Assert.IsNull(Hands.ActiveHandEntity);
+        Assert.That(Hands.ActiveHandEntity, Is.Null);
 
         // Open BUI
         await Interact();
@@ -30,18 +28,18 @@ public sealed class DispenserTest : InteractionTest
         await SendBui(ReagentDispenserUiKey.Key, ev);
 
         // Beaker is back in the player's hands
-        Assert.IsNotNull(Hands.ActiveHandEntity);
+        Assert.That(Hands.ActiveHandEntity, Is.Not.Null);
         AssertPrototype("Beaker", Hands.ActiveHandEntity);
 
         // Re-insert the beaker
         await Interact();
-        Assert.IsNull(Hands.ActiveHandEntity);
+        Assert.That(Hands.ActiveHandEntity, Is.Null);
 
         // Re-eject using the button directly instead of sending a BUI event. This test is really just a test of the
         // bui/window helper methods.
         await ClickControl<ReagentDispenserWindow>(nameof(ReagentDispenserWindow.EjectButton));
         await RunTicks(5);
-        Assert.IsNotNull(Hands.ActiveHandEntity);
+        Assert.That(Hands.ActiveHandEntity, Is.Not.Null);
         AssertPrototype("Beaker", Hands.ActiveHandEntity);
     }
 }