Add external cache usage for full tx retrieval which is used in batchDecorate

Author: oskarszoon

stores/utxo/aerospike/get.go

@@ -1316,6 +1316,17 @@ func (s *Store) GetTxFromExternalStore(ctx context.Context, previousTxHash chain
 		tracing.WithHistogram(prometheusTxMetaAerospikeMapGetExternal),
 	)
 
+	if s.externalTxCache != nil {
+		return s.externalTxCache.GetOrSet(previousTxHash, func() (*bt.Tx, bool, error) {
+			tx, err := s.getExternalTransaction(ctx, previousTxHash)
+			if err != nil {
+				return nil, false, err
+			}
+
+			return tx, true, nil
+		})
+	}
+
 	return s.getExternalTransaction(ctx, previousTxHash)
 }