[fix](load) Fix potential data loss during disk migration (apache#42296)

The following operations may trigger this issue.
1. migration start
2. load start using old tablet，but wait migration lock in
`RowsetBuilder::prepare_txn`.
3. migration finish, old tablet -> new tablet
4. obtained migration lock and commit successfully using old tablet.
5. publish failed using old tablet, because old tablet has been dropped.
It cause the data loss.

Therefore, after acquiring the migration lock, check if the tablet has
already been shut down. If it has, it indicates that it is an old
tablet, and data should not be imported into the old tablet.

be/src/olap/txn_manager.cpp

@@ -89,6 +89,15 @@ TxnManager::TxnManager(StorageEngine& engine, int32_t txn_map_shard_size, int32_
 Status TxnManager::prepare_txn(TPartitionId partition_id, const Tablet& tablet,
                                TTransactionId transaction_id, const PUniqueId& load_id,
                                bool ingest) {
+    // check if the tablet has already been shutdown. If it has, it indicates that
+    // it is an old tablet, and data should not be imported into the old tablet.
+    // Otherwise, it may lead to data loss during migration.
+    if (tablet.tablet_state() == TABLET_SHUTDOWN) {
+        return Status::InternalError<false>(
+                "The tablet's state is shutdown, tablet_id: {}. The tablet may have been dropped "
+                "or migrationed. Please check if the table has been dropped or try again.",
+                tablet.tablet_id());
+    }
     return prepare_txn(partition_id, transaction_id, tablet.tablet_id(), tablet.tablet_uid(),
                        load_id, ingest);
 }