Remove deprecated kwargs

ipu_config.json

@@ -2,16 +2,15 @@
     "recompute_checkpoint_every_layer": true,
     "optimizer_state_offchip": true,
     "replicated_tensor_sharding": true,
-    "enable_half_first_order_momentum": true,
     "enable_half_partials": true,
 
-    "replication_factor": {"pod4": 1, "pod8": 2, "pod16": 4, "pod32": 8, "pod64": 16, "default": 1},
+    "replication_factor": 1,
     "gradient_accumulation_steps": 512,
     "device_iterations": 1,
     "executable_cache_dir": "./exe_cache",
 
     "inference_device_iterations": 4,
-    "inference_replication_factor": {"pod4": 1, "pod8": 2, "pod16": 4, "pod32": 8, "pod64": 16, "default": 1},
+    "inference_replication_factor": 1,
     "ipus_per_replica": 4,
     "layers_per_ipu": [0, 4, 4, 4],
     "matmul_proportion": [0.25, 0.25, 0.25, 0.25]