enhance: Add streaming forward policy switch for delegator

[congqixia]

Related to #35303

[codecov]

Codecov Report

Attention: Patch coverage is 65.81633% with 67 lines in your changes missing coverage. Please review.

Project coverage is 82.34%. Comparing base (eb23e23) to head (dc97632).
Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/querynodev2/delegator/delta_forward.go	63.97%	61 Missing and 6 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #36330   +/-   ##
=======================================
  Coverage   82.34%   82.34%           
=======================================
  Files        1277     1277           
  Lines      150744   150825   +81     
=======================================
+ Hits       124126   124195   +69     
- Misses      21632    21645   +13     
+ Partials     4986     4985    -1     

Files with missing lines	Coverage Δ
internal/querynodev2/delegator/delegator_data.go	86.56% <100.00%> (+1.38%)	⬆️
internal/querynodev2/delegator/scalar_pruner.go	87.32% <ø> (ø)
pkg/util/paramtable/component_param.go	98.30% <100.00%> (+<0.01%)	⬆️
internal/querynodev2/delegator/delta_forward.go	63.97% <63.97%> (ø)

... and 33 files with indirect coverage changes

[XuanYang-cn]

/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: congqixia, XuanYang-cn

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• internal/querynodev2/delegator/OWNERS [congqixia]
• pkg/util/OWNERS [congqixia]

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