chore(spanner): throw aborted

Author: harshachinta

google-cloud-spanner/src/main/java/com/google/cloud/spanner/AsyncTransactionManagerImpl.java

@@ -80,6 +80,11 @@ public TransactionContextFutureImpl beginAsync() {
   }
 
   private ApiFuture<TransactionContext> internalBeginAsync(boolean firstAttempt) {
+    if (!firstAttempt) {
+      Preconditions.checkState(
+          txnState == TransactionState.ABORTED,
+          "resetForRetry can only be called after the transaction aborted.");
+    }
     txnState = TransactionState.STARTED;
 
     // Determine the latest transactionId when using a multiplexed session.