Fix qdrant index duplicates upon initialisation

[arkodoescode]

Issue: The Qdrant index does not implement _sync_index() and _remove_and_sync() methods and relies on add() method to add points upon initialisation. Also it does not generate UUIDs deterministically based on the utterance so every time it is initialised it creates a duplicate with a new ID.

Proposed fix:
There are two ways to go about this as far as I can see.

1. Generate UUIDs deterministically based on utterance so Qdrant internally updates the point instead of creating a duplicate. (This will not sync locally deleted utterances though, so not a complete solution)
2. Implement the sync methods.