[Bug] a lot of files in unsequence folder after old data migration

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/iotdb/issues) and found nothing similar.

### Version

Centos 7.4
0.13.4

### Describe the bug and provide the minimal reproduce step

After migrating data from another iotdb instance to the new one, there are a lot of files in unsequence folder, and the total file size is about 11G, meanwhile, the query performance is very poor for some query sql, which takes about 80+ seconds to finish the query.

### What did you expect to see?

the file size in unsequence folder decrease after run MERGE command in CLI and the query cost should be under 1s.

### What did you see instead?

nothing happen after running the MERGE command.

### Anything else?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Commencez par reproduire la migration depuis l’autre instance IoTDB, puis exécutez MERGE dans la CLI tout en surveillant le dossier unsequence et le temps d’exécution des requêtes. C’est terminé lorsque le nombre de fichiers unsequence diminue et que les requêtes concernées s’exécutent en moins d’une seconde.

Rédigé par le modèle d'indexation à partir du texte de l'issue.