Get rid of warnings in compositor tests

[pnuu]

This PR cleans the compositor tests so that they emit zero warnings when ran with pytest -Werror satpy/tests/test_composites.py satpy/tests/compositor_tests/.

The backwards incompatile change is the removal of GreenCorrector class, which is not used internally, and was deprecated in November 2022 in v0.39.0. Someone might be using it in their own configs.

The lower version limit of XArray is raised to v0.14.1 where xr.DataArray.drop_vars() was added and .drop() was deprecated.

Three deprecated AHI composites were removed, which were related to the deprecation of GreenCorrector.

• Tests adjusted

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (338817d) 95.32% compared to head (336fc9c) 95.32%.
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2684   +/-   ##
=======================================
  Coverage   95.32%   95.32%           
=======================================
  Files         371      371           
  Lines       52435    52427    -8     
=======================================
- Hits        49982    49975    -7     
+ Misses       2453     2452    -1     

Flag	Coverage Δ
behaviourtests	4.16% <0.00%> (+<0.01%)	⬆️
unittests	95.94% <100.00%> (+<0.01%)	⬆️

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[coveralls]

Pull Request Test Coverage Report for Build 7182050794

• 4 of 4 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.001%) to 95.887%

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Totals
Change from base Build 7180375207:	0.001%
Covered Lines:	50101
Relevant Lines:	52250

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💛 - Coveralls