enhance: Support new RESTful URL to describe import job (#36753)

[bigsheeper]

Support the new RESTful URL for retrieving/describing import progress: /v2/vectordb/jobs/import/describe.
Deprecate the old URL: /v2/vectordb/jobs/import/get_progress.

issue: #36752

pr: #36753

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.23%. Comparing base (c69af44) to head (c3eb3e2).
Report is 5 commits behind head on 2.4.

Additional details and impacted files

@@            Coverage Diff             @@
##              2.4   #36754      +/-   ##
==========================================
+ Coverage   71.95%   81.23%   +9.27%     
==========================================
  Files        1064     1064              
  Lines      140580   140581       +1     
==========================================
+ Hits       101159   114194   +13035     
+ Misses      35093    22050   -13043     
- Partials     4328     4337       +9     

Files with missing lines	Coverage Δ
...nternal/distributed/proxy/httpserver/handler_v2.go	91.81% <100.00%> (+<0.01%)	⬆️

... and 228 files with indirect coverage changes

[czs007]

/approve
/lgtm

[sre-ci-robot]

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