Prevent obsolete reports about failure of cleaning viewer instances

[Czaki]

Description

This is often the thing that if the test is failed, then cleaning of the viewer is failed. At the make_napari_viewer fixture is long, most of the error log is occupied by information of failure in the fixture, not the actual error message.

We also do not clean instances, so the next test crash because of the previous test crash. I have added a clean step to prevent this.

Type of change

• Bug-fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

References

How has this been tested?

• example: the test suite for my feature covers cases x, y, and z
• example: all tests pass with my change
• example: I check if my changes works with both PySide and PyQt backends
  as there are small differences between the two Qt bindings.

Final checklist:

• My PR is the minimum possible work for the desired functionality
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• If I included new strings, I have used trans. to make them localizable.
  For more information see our translations guide.

[codecov]

Codecov Report

Merging #5317 (4211b18) into main (8a78b3c) will increase coverage by 0.01%.
The diff coverage is 62.50%.

@@            Coverage Diff             @@
##             main    #5317      +/-   ##
==========================================
+ Coverage   89.07%   89.08%   +0.01%     
==========================================
  Files         581      581              
  Lines       49233    49241       +8     
==========================================
+ Hits        43853    43866      +13     
+ Misses       5380     5375       -5     

Impacted Files	Coverage Δ
napari/utils/_testsupport.py	63.55% <62.50%> (-0.08%)	⬇️
napari/layers/image/image.py	95.92% <0.00%> (+0.23%)	⬆️
napari/utils/theme.py	89.79% <0.00%> (+0.68%)	⬆️
napari/utils/info.py	83.33% <0.00%> (+1.11%)	⬆️
napari/layers/image/_image_slice.py	100.00% <0.00%> (+2.38%)	⬆️
napari/_qt/__init__.py	55.17% <0.00%> (+6.89%)	⬆️
...layers/image/experimental/_chunked_image_loader.py	96.00% <0.00%> (+8.00%)	⬆️

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[brisvag]

If I understand correctly what this fixes, thanks so much! This has been annoying me to no end 😆

I don't quite follow the first chunk of code though.

[Carreau]

LGTM.

[Carreau]

I'm not sure why i didn't do that originally.