Backport PR #2362 on branch 0.12.x (chore: add sparse index dtype checks to assert_equal)

[meeseeksmachine]

Backport PR #2362: chore: add sparse index dtype checks to assert_equal

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.88%. Comparing base (e54fc74) to head (a671663).
⚠️ Report is 1 commits behind head on 0.12.x.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           0.12.x    #2371      +/-   ##
==========================================
- Coverage   86.93%   84.88%   -2.05%     
==========================================
  Files          46       46              
  Lines        7270     7273       +3     
==========================================
- Hits         6320     6174     -146     
- Misses        950     1099     +149     

Files with missing lines	Coverage Δ
src/anndata/tests/helpers.py	83.33% <100.00%> (-9.60%)	⬇️

... and 6 files with indirect coverage changes