chore(ordered-partial-aggregate): move OrderedPartialAggregateStream to generators for readability

[rluvaton]

Which issue does this PR close?

N/A

Rationale for this change

Simplify the code by making it linear and with less state to hold in mind

What changes are included in this PR?

change OrderedPartialAggregateStream into async generators

Are these changes tested?

existing tests

Are there any user-facing changes?

no

[rluvaton]

@2010YOUY01 can you please run the benchmark that you think are the most appropriate here and review

[codecov-commenter]

Codecov Report

❌ Patch coverage is 88.40580% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.69%. Comparing base (1c3232c) to head (5c3ef5c).
⚠️ Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
...ical-plan/src/aggregates/ordered_partial_stream.rs	89.39%	0 Missing and 7 partials ⚠️
datafusion/physical-plan/src/aggregates/mod.rs	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #23951      +/-   ##
==========================================
+ Coverage   80.67%   80.69%   +0.02%     
==========================================
  Files        1095     1095              
  Lines      372376   372447      +71     
  Branches   372376   372447      +71     
==========================================
+ Hits       300397   300563     +166     
+ Misses      54052    53913     -139     
- Partials    17927    17971      +44     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.