fix: Isolate faiss_hnsw and hnsw by index version

[foxspy]

issue: milvus-io/milvus#37665
Considering the compatibility during the distributed system upgrade, faiss_hnsw and hnswlib must be isolated by version on both the read and write path; for version <= 5, these indexes will be processed by hnswlib; otherwise, they will be processed by faiss; the maximum availability of index version during the upgrade process has been guaranteed in the early stage

[mergify]

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[foxspy]

/kind improvement

[liliu-z]

/lgtm

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.36%. Comparing base (3c46f4c) to head (6a9d61e).
Report is 255 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##           main     #952       +/-   ##
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+ Coverage      0   74.36%   +74.36%     
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  Files         0       82       +82     
  Lines         0     6682     +6682     
=========================================
+ Hits          0     4969     +4969     
- Misses        0     1713     +1713     

see 82 files with indirect coverage changes