[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!

Beginne damit, die Migration von der anderen IoTDB-Instanz zu reproduzieren, und führe anschließend MERGE in der CLI aus, während du den Ordner unsequence und die Abfragezeiten überwachst. Als abgeschlossen gilt die Aufgabe, wenn die unsequence-Dateien weniger werden und die betroffenen Abfragen in unter einer Sekunde abgeschlossen sind.

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