Fix SupbaseVectoreStore write operation timeout (#12318)
**Description**
This small change will make chunk_size a configurable parameter for
loading documents into a Supabase database.
**Issue**
https://github.com/langchain-ai/langchain/issues/11422
**Dependencies**
No chanages
**Twitter**
@ j1philli
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Co-authored-by: Greg Richardson <greg.nmr@gmail.com>
