Removes unsupported (deprecated and unused) IPUConfig params from older configs (these will raise an error in latest build of Optimum Graphcore)

ipu_config.json

@@ -4,7 +4,6 @@
   "embedding_serialization_factor": 2,
   "enable_half_partials": true,
   "executable_cache_dir": "./exe_cache",
-  "execute_encoder_on_cpu_for_generation": false,
   "gradient_accumulation_steps": 2048,
   "inference_device_iterations": 5,
   "inference_replication_factor": {"pod4": 1, "pod8": 2, "pod16": 4, "pod32": 8, "pod64": 16, "default": 4},
@@ -22,7 +21,5 @@
   "recompute_checkpoint_every_layer": true,
   "replicated_tensor_sharding": true,
   "replication_factor": {"pod4": 1, "pod8": 2, "pod16": 4, "pod32": 8, "pod64": 16, "default": 4},
-  "seed": 42,
-  "sharded_execution_for_inference": false,
-  "transformers_version": "4.20.1"
+  "seed": 42
 }