Test full Dask support for log1p, normalize_per_cell, filter_cells/filter_genes

[flying-sheep]

• Closes Test full dask support for log1p, normalize_per_cell, filter_cells/filter_genes #2813
• Tests included or not required because:

• Release notes not necessary because: only dev changes

this tests that log1p, normalize_per_cell, filter_cells, and filter_genes return dask arrays when handed dask arrays.

[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (4f4b1c3) 72.70% compared to head (b4a913d) 72.72%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2814      +/-   ##
==========================================
+ Coverage   72.70%   72.72%   +0.01%     
==========================================
  Files         111      111              
  Lines       12368    12384      +16     
==========================================
+ Hits         8992     9006      +14     
- Misses       3376     3378       +2     

Files	Coverage Δ
scanpy/_compat.py	50.00% <100.00%> (+5.55%)	⬆️
scanpy/preprocessing/_simple.py	83.13% <80.00%> (ø)
scanpy/preprocessing/_distributed.py	82.60% <80.00%> (-0.73%)	⬇️