(chore): tighten spmatrix usage

[ilan-gold]

• Closes (chore): clean up use of spmatrix and sparray #1649
• Tests added
• Release note added (or unnecessary)

[ilan-gold]

Problematically, older scanpy versions have the read import and we probably want to support older versions for a while since https://github.com/scverse/scanpy/tree/6d234a7ec8c33348b7778e9ccb8fe7f226e4723d is only three weeks old. So fixing this probably requires bumping the minimum supported version of scanpy with anndata, which I don't think we are ready to do.

[codecov]

Codecov Report

Attention: Patch coverage is 96.55172% with 1 line in your changes missing coverage. Please review.

Project coverage is 82.99%. Comparing base (af6480e) to head (8ea1c4e).

Files with missing lines	Patch %	Lines
src/anndata/tests/helpers.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1767      +/-   ##
==========================================
- Coverage   87.01%   82.99%   -4.02%     
==========================================
  Files          40       40              
  Lines        6059     6056       -3     
==========================================
- Hits         5272     5026     -246     
- Misses        787     1030     +243     

Files with missing lines	Coverage Δ
src/anndata/_core/aligned_mapping.py	93.38% <100.00%> (-0.03%)	⬇️
src/anndata/_core/anndata.py	83.58% <100.00%> (-0.14%)	⬇️
src/anndata/_core/index.py	94.96% <100.00%> (ø)
src/anndata/_core/merge.py	83.88% <100.00%> (-11.11%)	⬇️
src/anndata/_core/raw.py	76.97% <100.00%> (-4.32%)	⬇️
src/anndata/_core/sparse_dataset.py	93.02% <100.00%> (ø)
src/anndata/_core/storage.py	91.89% <100.00%> (-8.11%)	⬇️
src/anndata/_io/h5ad.py	93.00% <ø> (ø)
src/anndata/_io/specs/methods.py	88.11% <100.00%> (-0.43%)	⬇️
src/anndata/compat/__init__.py	72.80% <100.00%> (-12.56%)	⬇️
... and 2 more

... and 7 files with indirect coverage changes

[ilan-gold]

Since this isn't until 0.12 I would like to wait to see if numba comes out with python 3.13 support and then drop 3.10 and do all of the scientific python ecosystem all at once: #1768

Then we don't have to worry about register