Finish scale→density_norm deprecation

[flying-sheep]

sc.pl.violin and sc.pl.stacked_violin were missed in #2844

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.77%. Comparing base (bd75839) to head (32279bf).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3244      +/-   ##
==========================================
+ Coverage   76.49%   76.77%   +0.27%     
==========================================
  Files         109      109              
  Lines       12544    12550       +6     
==========================================
+ Hits         9596     9635      +39     
+ Misses       2948     2915      -33     

Files with missing lines	Coverage Δ
src/scanpy/plotting/_anndata.py	85.02% <100.00%> (+0.03%)	⬆️
src/scanpy/plotting/_stacked_violin.py	84.57% <100.00%> (ø)
src/scanpy/plotting/_tools/__init__.py	77.60% <100.00%> (ø)
src/scanpy/plotting/_utils.py	56.56% <100.00%> (+0.32%)	⬆️

... and 2 files with indirect coverage changes