Fix txlist RPC endpoint to use the token info for fee currencies

The txlist RPC endpoint uses the CeloParams table to fetch names of stable
tokens used as gas currencies. It can take it from the Tokens table instead.

apps/explorer/lib/explorer/etherscan.ex

@@ -8,7 +8,7 @@ defmodule Explorer.Etherscan do
   alias Explorer.Etherscan.Logs
   alias Explorer.{Chain, Repo}
   alias Explorer.Chain.Address.{CurrentTokenBalance, TokenBalance}
-  alias Explorer.Chain.{Address, Block, CeloParams, Hash, InternalTransaction, Log, TokenTransfer, Transaction}
+  alias Explorer.Chain.{Address, Block, CeloParams, Hash, InternalTransaction, Log, Token, TokenTransfer, Transaction}
   alias Explorer.Chain.Transaction.History.TransactionStats
 
   @default_options %{
@@ -490,16 +490,16 @@ defmodule Explorer.Etherscan do
         t in Transaction,
         join: a in ^addresses_wrapped_subquery,
         on: t.hash == a.hash,
-        left_join: p in CeloParams,
-        on: t.gas_currency_hash == p.address_value,
+        left_join: k in Token,
+        on: t.gas_currency_hash == k.contract_address_hash,
         inner_join: b in Block,
         on: b.number == t.block_number,
         order_by: [{^options.order_by_direction, t.block_number}],
         limit: ^options.page_size,
         offset: ^offset(options),
         select:
           merge(map(t, ^@transaction_fields), %{
-            fee_currency: p.name,
+            fee_currency: k.symbol,
             block_timestamp: b.timestamp,
             confirmations: fragment("? - ?", ^max_block_number, t.block_number)
           })