Disable flaky python callback test.

PiperOrigin-RevId: 575893965

tests/jaxpr_effects_test.py

@@ -605,6 +605,8 @@ def f(x):
     jax.effects_barrier()
     self.assertListEqual(log, [2., 3.])
 
+  # TODO(b/307211483): Investigate failure
+  @jtu.skip_on_devices("tpu")
   def test_ordered_effect_remains_ordered_across_multiple_devices(self):
     if jax.device_count() < 2:
       raise unittest.SkipTest("Test requires >= 2 devices.")
@@ -632,8 +634,8 @@ def g(x):
     f(jnp.ones((500, 500)))
     g(3.)
     jax.effects_barrier()
-    x_, y_ = float(jnp.log(1.25e8)), 3.
-    expected_log = [x_, y_, x_, y_, x_, y_]
+    f_, g_ = float(jnp.log(1.25e8)), 3.
+    expected_log = [f_, g_, f_, g_, f_, g_]
     self.assertListEqual(log, expected_log)
 
   def test_different_threads_get_different_tokens(self):