fix(rag): Fix bug fail to delete files when deleting the knowledge space

[toralee]

Description

Fix delete the knowldege uploading file in the 'pilot/data' when deleteing the space by dbgpt CLI. There's no dependencies that are required for this change.

How Has This Been Tested?

On the command terminal, executing dbgpt knowledge load --space_name testnewspace --local_doc_path \testpath\testfile.txt, and then executing dbgpt knowledge delete --sapce_name testnewspace. From observing the direcotry $(dbgpt_path)/pilot/data/.

Snapshots:

Include snapshots for easier review.

Checklist:

• My code follows the style guidelines of this project
• I have already rebased the commits and make the commit message conform to the project standard.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Any dependent changes have been merged and published in downstream modules

[csunny]

Thanks for your PR. LGTM

[fangyinc]

Thanks for your PR.
LGTM.