Fix cross-thread report assertion

- Assert the spawn failure report through the bound platform instead of a thread-confined static mock, so the report is seen whichever thread wins the reporting race
- Guard WorldEntitySpawnerLifecycleTest against a leaked platform binding
- Unbind the stub platform after the probe module's platform state test

probe/src/test/java/art/arcane/iris/probe/StubPlatformStateTest.java

@@ -5,6 +5,7 @@ import art.arcane.iris.engine.object.IrisObjectRotation;
 import art.arcane.iris.spi.IrisPlatforms;
 import art.arcane.iris.spi.PlatformBlockState;
 import art.arcane.iris.util.project.hunk.Hunk;
+import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -21,6 +22,11 @@ public final class StubPlatformStateTest {
         StubPlatform.bindGenerationStateHandlers();
     }
 
+    @AfterClass
+    public static void unbindPlatform() {
+        IrisPlatforms.unbind();
+    }
+
     @Test
     public void rotatesFacingAxisAndConnectedFaces() {
         IrisObjectRotation rotation = IrisObjectRotation.of(0, 90, 0);