Tests: Disable LibThreading detach tests for now

These tests don't pass (at least not without KVM) at the moment,
so let's not run them on CI.

Tests/LibThreading/TestThread.cpp

@@ -8,6 +8,9 @@
 #include <LibThreading/Thread.h>
 #include <unistd.h>
 
+// FIXME: Enable these tests once they work reliably.
+
+#if 0
 TEST_CASE(threads_can_detach)
 {
     int should_be_42 = 0;
@@ -32,3 +35,4 @@ TEST_CASE(joining_detached_thread_errors)
 
     EXPECT(thread->join().is_error());
 }
+#endif