Revise backoff implementation for Async weaviate knowledgebase.

[jacobthebanana]

Describe the bug

Backoff isn't handling a certain number of exceptions in the Async Weaviate knowledge base tool implementation.

To Reproduce

Run with concurrency of e.g., 36 and see the exceptions show up.

Expected behavior

Exponential backoff should be activated when any weaviate connectivity error happens.

Screenshots

If applicable, add screenshots to help explain your problem.

Version

• Version info such as v0.1.5

Additional context

Possible fix- instead of relying on backoff which allows only built-in exceptions, do the exception handling ourselves and throw e.g., a classic Runtime error which we handle using backoff.