Apply Fable self-audit fixes to Llama distribution tests

- Use preset_utils.load_json instead of hand-rolled get_file+open+
  json.load in test_layout_map_live_presets, matching the cached
  Gemini load_json/encoding suggestion (adds encoding="utf-8").
- Fix test_distribution_with_lora's device-count guard to
  `len(devices) < 2`, matching the shared helper and every sibling
  check instead of the fragile `== 1`.

Author: pctablet505

keras_hub/src/models/llama/llama_backbone_test.py

@@ -1,5 +1,4 @@
 import gc
-import json
 import os
 import re
 
@@ -10,8 +9,7 @@
 
 from keras_hub.src.models.llama.llama_backbone import LlamaBackbone
 from keras_hub.src.tests.test_case import TestCase
-from keras_hub.src.utils.preset_utils import CONFIG_FILE
-from keras_hub.src.utils.preset_utils import get_file
+from keras_hub.src.utils.preset_utils import load_json
 
 # Dims for the Tier-2 CI-safe mesh-shape sweep: representative real-preset
 # dimensions, frozen as literals and sourced once, offline -- do not add a
@@ -209,7 +207,7 @@ def test_distribution_with_lora(self):
         if keras.backend.backend() != "jax":
             self.skipTest("`ModelParallel` testing requires the Jax backend.")
         devices = keras.distribution.list_devices("CPU")
-        if len(devices) == 1:
+        if len(devices) < 2:
             # Need more than 1 device for distribution testing.
             self.skipTest("`ModelParallel` testing requires multiple devices.")
         # Pinned to exactly 2 devices -- see test_distribution's comment.
@@ -330,9 +328,7 @@ def test_layout_map_live_presets(self):
         fetch_failures = []
         for preset in LlamaBackbone.presets:
             try:
-                path = get_file(preset, CONFIG_FILE)
-                with open(path) as f:
-                    cfg = json.load(f)["config"]
+                cfg = load_json(preset)["config"]
             except Exception as e:
                 # A preset this account can't reach (e.g. an unaccepted
                 # Kaggle license consent click-through, or no