Cleanup integration tests prototype usage, naming and unused variables (#3114)

* Fix naming of prototypes variable in tests

* Remove unused variables in tests

* Remove unused variables in tests

* Replace content entities with test entities

* Fix airlock and lung test

Content.IntegrationTests/Tests/Pulling/PullTest.cs

@@ -16,7 +16,7 @@ namespace Content.IntegrationTests.Tests.Pulling
     [TestOf(typeof(PullController))]
     public class PullTest : ContentIntegrationTest
     {
-        private const string PROTOTYPES = @"
+        private const string Prototypes = @"
 - type: entity
   name: PullTestPullerDummy
   id: PullTestPullerDummy
@@ -35,7 +35,7 @@ namespace Content.IntegrationTests.Tests.Pulling
         [Test]
         public async Task AnchoredNoPullTest()
         {
-            var options = new ServerContentIntegrationOption {ExtraPrototypes = PROTOTYPES};
+            var options = new ServerContentIntegrationOption {ExtraPrototypes = Prototypes};
             var server = StartServerDummyTicker(options);
 
             await server.WaitIdleAsync();