fix(milvus): Fix milvus store search with topk always set to 4

[slper001]

Description

Previously, the search topk in Milvus storage was always fixed at 4. This commit fixes the issue by allowing users to specify topk dynamically.

How Has This Been Tested?

When the parameter VECTOR_STORE_TYPE is set to Milvus, the KNOWLEDGE_SEARCH_TOP_SIZE parameter becomes ineffective, and the system can only match up to 4 documents from the Milvus database. The issue lies in the _search method of the MilvusStore class, where the letter k represents the meaning of topk and is set to a default value of 4. However, during the method call, the keyword argument passed is topk (instead of k), causing the parameter to be ignored and the value of k to remain fixed at the default value of 4.

After I modified the keyword argument passed during the method call, the KNOWLEDGE_SEARCH_TOP_SIZE parameter started working as expected.

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

[Aries-ckt]

Thanks for your contribution, LGTM.

[yhjun1026]

r+