Remove trailing commas on wallet account ls output

The trailing commas is inconvenient:

1. For users trying to select an account id by double-clicking it in a terminal: the comma gets included in the selection
2. For dev parsing the `wallet account list` output: the commas needs to be handled

wallet/src/cli/account.rs

@@ -278,7 +278,7 @@ impl WalletSubcommand for AccountSubcommand {
                             .iter()
                             .map(|(id, chain_index)| format!("{chain_index} Private/{id}")),
                     )
-                    .format(",\n");
+                    .format("\n");
 
                 println!("{accounts}");
                 Ok(SubcommandReturnValue::Empty)