Mark phi3 real multi-device tests with @pytest.mark.multi_device

test_distribution and test_layout_map_mesh_shapes both construct a real
DeviceMesh/ModelParallel and need multiple simulated devices to mean
anything, but neither carried the multi_device marker that PR keras-team#2809's
dedicated CI job filters on. Without it, that job silently collects zero
tests from this model. test_layout_map_live_presets already had the
marker and stays excluded by design (kaggle_key_required + extra_large).

For test_layout_map_mesh_shapes, the marker must go directly on the
function, below @parameterized.named_parameters (not above it) --
absl.testing.parameterized's generated per-case methods only pick up
pytestmark via functools.wraps when the mark decorates the original
function itself; decorating the _ParameterizedTestIter object produced
by named_parameters(...) does not propagate pytestmark to the expanded
test cases. Verified empirically: outermost placement collected 0 of 12
parameterized cases under the marker filter, innermost placement
collected all 12.

Author: pctablet505

keras_hub/src/models/phi3/phi3_backbone_test.py

@@ -147,6 +147,7 @@ def test_saved_model(self):
             input_data=self.input_data,
         )
 
+    @pytest.mark.multi_device
     def test_distribution(self):
         # Note (preserved from the pre-refactor manual test): the default
         # test config's num_key_value_heads=2 divides the pinned 2-device
@@ -230,6 +231,7 @@ def test_all_presets(self):
         for dims in (PHI3_MINI_DIMS, PHI3_SMALL_GQA_DIMS)
         for shape in CAPPED_MESH_SHAPES
     )
+    @pytest.mark.multi_device
     def test_layout_map_mesh_shapes(self, dims, mesh_shape):
         if keras.backend.backend() != "jax":
             self.skipTest("`ModelParallel` testing requires the Jax backend.")