pindexer: don't index transactions with no actions

There are a few of these on mainnet before we added the check,
and they yield the same transaction ID. These are completely uninteresting
transactions which have no effect on any state on the chain,
and we should ignore them. Other transactions should be unique.

crates/bin/pindexer/src/dex_ex/mod.rs

@@ -1407,14 +1407,17 @@ impl Component {
         transaction_id: [u8; 32],
         transaction: Transaction,
     ) -> anyhow::Result<()> {
+        if transaction.transaction_body.actions.is_empty() {
+            return Ok(());
+        }
         sqlx::query(
             "INSERT INTO dex_ex_transactions (
                 transaction_id,
                 transaction,
                 height,
                 time
             ) VALUES ($1, $2, $3, $4)
-            ON CONFLICT (transaction_id) DO NOTHING",
+            ",
         )
         .bind(transaction_id)
         .bind(transaction.encode_to_vec())