Backport PR #4013 on branch 1.12.x (perf: "two-pass" seurat hvg via scanpy.get.aggregate)

[meeseeksmachine]

Backport PR #4013: perf: "two-pass" seurat hvg via scanpy.get.aggregate

[codecov]

Codecov Report

❌ Patch coverage is 90.47619% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.62%. Comparing base (1075bbc) to head (cbf34c4).
⚠️ Report is 1 commits behind head on 1.12.x.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/scanpy/preprocessing/_highly_variable_genes.py	90.47%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           1.12.x    #4186      +/-   ##
==========================================
+ Coverage   78.61%   78.62%   +0.01%     
==========================================
  Files         121      121              
  Lines       12693    12707      +14     
==========================================
+ Hits         9978     9991      +13     
- Misses       2715     2716       +1     

Flag	Coverage Δ
hatch-test.low-vers	77.68% <90.47%> (+0.01%)	⬆️
hatch-test.pre	78.51% <90.47%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/scanpy/preprocessing/_highly_variable_genes.py	94.59% <90.47%> (-0.45%)	⬇️

... and 1 file with indirect coverage changes