fix: Unify loaded partition check to delegator

[congqixia]

Related to #36370

[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/querynodev2/delegator/OWNERS [congqixia]
• internal/querynodev2/segments/OWNERS [congqixia]
• internal/querynodev2/tasks/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 97.05882% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.52%. Comparing base (b0d5866) to head (55a4cef).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/querynodev2/segments/validate.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #36879      +/-   ##
==========================================
+ Coverage   81.51%   81.52%   +0.01%     
==========================================
  Files        1308     1308              
  Lines      156200   156208       +8     
==========================================
+ Hits       127324   127347      +23     
+ Misses      23753    23749       -4     
+ Partials     5123     5112      -11     

Files with missing lines	Coverage Δ
internal/querynodev2/delegator/delegator.go	86.84% <100.00%> (+0.24%)	⬆️
internal/querynodev2/segments/retrieve.go	85.57% <100.00%> (ø)
internal/querynodev2/tasks/search_task.go	85.64% <100.00%> (ø)
internal/querynodev2/segments/validate.go	70.27% <50.00%> (-4.09%)	⬇️

... and 28 files with indirect coverage changes

[weiliu1031]

/lgtm