Fix MODIS readers chunking compatibility with newer dask

[djhoese]

Triggered by changes in dask (see dask/dask#11341), but I think the main issue is that I was specifying previous_chunks with -1 which I can understand would be confusing if dask assumes "yeah this is what the chunks are now".

This should fix unstable tests related to MODIS readers.

• Closes #xxxx
• Tests added
• Fully documented
• Add your name to AUTHORS.md if not there already

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.08%. Comparing base (f36a096) to head (28a793c).
Report is 11 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2965   +/-   ##
=======================================
  Coverage   96.08%   96.08%           
=======================================
  Files         377      377           
  Lines       55125    55134    +9     
=======================================
+ Hits        52967    52976    +9     
  Misses       2158     2158           

Flag	Coverage Δ
behaviourtests	3.94% <ø> (-0.01%)	⬇️
unittests	96.18% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[coveralls]

Pull Request Test Coverage Report for Build 11669429986

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.001%) to 96.192%

---

Files with Coverage Reduction	New Missed Lines	%
satpy/tests/writer_tests/test_cf.py	1	99.14%

Totals
Change from base Build 11634318306:	0.001%
Covered Lines:	53220
Relevant Lines:	55327

---

💛 - Coveralls

[mraspaud]

LGTM