Backport PR #2351: fix: check .raw length on setting

[flying-sheep]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 95.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.86%. Comparing base (7f67bee) to head (25b7a85).
⚠️ Report is 1 commits behind head on 0.12.x.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/anndata/_core/anndata.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           0.12.x    #2354      +/-   ##
==========================================
- Coverage   86.90%   84.86%   -2.04%     
==========================================
  Files          46       46              
  Lines        7260     7269       +9     
==========================================
- Hits         6309     6169     -140     
- Misses        951     1100     +149     

Files with missing lines	Coverage Δ
src/anndata/_core/raw.py	76.87% <100.00%> (-2.99%)	⬇️
src/anndata/_core/anndata.py	83.82% <88.88%> (+0.01%)	⬆️

... and 6 files with indirect coverage changes