Fix databricks vector search metadata

[Data-drone]

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes # (issue)

When using Databricks Vector Search as a storage context then it duplicated the "doc_id" column resulting in:
errors when trying to use it as a retriever. This fix made the integration class work

Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• [ X] Yes

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• I ran the example as per: https://docs.llamaindex.ai/en/stable/examples/vector_stores/DatabricksVectorSearchDemo/ and it worked this time rather than erroring out due to the doc_id column being duplicated

Suggested Checklist:

• [ X] I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I ran make format; make lint to appease the lint gods