Remove deprecated/unused params

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

ipu_config.json

@@ -22,10 +22,8 @@
   "optimizer_state_offchip": true,
   "optimum_version": "1.0.0",
   "output_mode": "final",
-  "profile_dir": "",
   "recompute_checkpoint_every_layer": true,
   "replicated_tensor_sharding": true,
   "replication_factor": 2,
   "seed": 42,
-  "use_popdist": false
 }