[Bug] Csv import meet error "There are too many timeseries in memory"

### Search before asking

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

### Version

1.0.0

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

Meet this error when import data to iotdb(version: 1.0.0):
"Meet error when insert csv because 507: There are too many timeseries in memory, please increase MAX_HEAP_SIZE in datanode-env.sh/bat, restart and create timeseries again."

Are there any other options or configurations to avoid this as for now i can`t increase memory size of the server? I don't understand why there are so many timeseries in memory, as there are no queries at the moment. If these timeseries in memory are cache of imported data, when will the memory will be released?

### What did you expect to see?

-

### What did you see instead?

-

### Anything else?

_No response_

### Are you willing to submit a PR?

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

まず IoTDB 1.0.0 で CSV インポートの失敗を再現し、datanode-env.sh/bat で参照されている timeseries-memory の制限を調査します。クエリを実行していないのにインポートが制限に達する理由と、メモリが解放されるかどうかを特定します。原因と、ヒープサイズを増やせないサーバー向けのサポート対象の設定または回避策を文書化できれば完了です。

索引モデルが issue の本文から書いたものです。