fix the issue that OceanBase config in .env does not take effect

[GITHUBear]

Description

OceanBaseConfig items override the configurations in .env because OceanBaseConfig items set the default values.

How Has This Been Tested?

• Test the knowledge base function using OceanBase + DB-GPT.
• make fmt
• make mypy
• make test

Snapshots:

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]

r+

[Aries-ckt]

r+