Upsert method missing ID field

[hardiklakhalani]

I want to update the document using addDocument().
When upsert method is called while autoID is set false, it's being added instead of update.

The following existing code's logic removes the autoID by splicing it.
https://github.com/langchain-ai/langchainjs/blob/66ca089d126aeba7a7114735516b9134d6272fbc/libs/langchain-community/src/vectorstores/milvus.ts#L575C4-L594C8

Due to that. This switch case's if-else condition always returns false because of a missing ID
https://github.com/langchain-ai/langchainjs/blob/66ca089d126aeba7a7114735516b9134d6272fbc/libs/langchain-community/src/vectorstores/milvus.ts#L265C6-L297C10