Change ESSL colorisation approach

[gerritholl]

Change the approach for ESSL colorisation. Remove the dedicated class and instead define a colourmap to be used with the colorize enhancement. Fix the ratio to be the right way around.

Fixes and closes 3020.

• Closes Re-implement essl_colorized_low_level_moisture using colorize #3020

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.08%. Comparing base (5984c29) to head (b3e3b31).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3021      +/-   ##
==========================================
- Coverage   96.10%   96.08%   -0.02%     
==========================================
  Files         377      375       -2     
  Lines       55163    55103      -60     
==========================================
- Hits        53012    52944      -68     
- Misses       2151     2159       +8     

Flag	Coverage Δ
behaviourtests	3.93% <ø> (-0.02%)	⬇️
unittests	96.17% <ø> (-0.02%)	⬇️

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[coveralls]

Pull Request Test Coverage Report for Build 12651965186

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.
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• 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.
• 8 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.02%) to 96.188%

---

Files with Coverage Reduction	New Missed Lines	%
satpy/tests/utils.py	2	93.16%
satpy/tests/reader_tests/gms/test_gms5_vissr_l1b.py	3	98.67%
satpy/tests/reader_tests/gms/test_gms5_vissr_navigation.py	3	97.18%

Totals
Change from base Build 12299617024:	-0.02%
Covered Lines:	53186
Relevant Lines:	55294

---

💛 - Coveralls

[mraspaud]

Thanks for the PR! Can we have a before/after image comparison?

[gerritholl]

Before :

After:

We see a difference only in the noise part at night, probably because the ratio is defined the other way around.