Remove gas fees model dependency on functions

.spice/models/gas_fees/model.yml

@@ -1,9 +1,9 @@
 family: gas_fees
 name: v0.0
 model_type: gasfees_v1
-handler: gas_fees_v2.py
-training_entry_point: gas_fees_v2.train
-inference_entry_point: gas_fees_v2.infer
+handler: null
+training_entry_point: null
+inference_entry_point: null
 training_query: 'WITH counts AS (    SELECT block_number, count(1) as "count" FROM eth.transactions GROUP BY block_number  )  SELECT number as "ts", CAST(b.base_fee_per_gas / 1000000000.0 AS DOUBLE) as "y", CAST(c."count" AS DOUBLE) as "covariate"  FROM eth.blocks b  INNER JOIN counts c ON b.number = c.block_number  WHERE b.base_fee_per_gas IS NOT NULL ORDER BY block_number DESC LIMIT 500'
 inference_query: 'SELECT number as "ts", CAST(base_fee_per_gas / 1000000000.0 AS DOUBLE) as "y", CAST(transaction_count AS DOUBLE) as "y2" from eth.recent_blocks WHERE base_fee_per_gas IS NOT NULL ORDER BY ts DESC LIMIT 35'
 lookback_size: 30