Asset Type is incorrect enum in contract_data

[sydneynotthecity]

While working on data quality tests, I found that assetType has following values in stg_contract_data

• AssetTypeAssetTypeCreditAlphanum4

Acceptable values are 'credit_alphanum4', 'credit_alphanum12', 'native'

Ref: https://stellarfoundation.slack.com/archives/C071DNLU4JC/p1728081984293059

This ticket requires to fix the code creating these values and backfill the existing data. Note: if we do decide to fix this bug in the raw transformation layer, we will need to coordinate backfills with Nansen and Dune, who use Hubble as their source of record. It may not be ideal to fix in the raw, and might be worth mapping correctly within dbt instead.