fix: [2.4] Check target partition load state only when dropping partition (#38375)

[congqixia]

Cherry pick from master
pr: #38375
Related to #38372

This PR make drop partition only check target partition load states only in case of concurrent releasing other partition in same collection.

---

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: congqixia

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• internal/proxy/OWNERS [congqixia]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 80.40%. Comparing base (e959860) to head (0920d70).
Report is 1 commits behind head on 2.4.

Files with missing lines	Patch %	Lines
internal/proxy/util.go	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              2.4   #38394      +/-   ##
==========================================
+ Coverage   79.44%   80.40%   +0.96%     
==========================================
  Files        1077     1077              
  Lines      169027   169022       -5     
==========================================
+ Hits       134277   135909    +1632     
+ Misses      30276    28654    -1622     
+ Partials     4474     4459      -15     

Files with missing lines	Coverage Δ
internal/proxy/util.go	90.66% <57.14%> (-0.16%)	⬇️

... and 95 files with indirect coverage changes

[tedxu]

/lgtm