Remove final portion of the TxOut item local encryption
Follow up on !2821 (merged) that removed the encryption pathway for the local storage of TxOut items.
Resolves !1632 (merged) which also contains the rationale behind the removal, as well as removing the sole usage of MD5 in the codebase.
Not to be merged until we are sure all active nodes have churned through the TxOut kv-store with the new pathway in !2821 (merged).