[Fixes #12455] Map thumbnails extent always cover the whole globe

[mattiagiupponi]

Checklist

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 73.91304% with 6 lines in your changes missing coverage. Please review.

Project coverage is 64.15%. Comparing base (2e4dae2) to head (a52900d). Report is 27 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #12460      +/-   ##
==========================================
- Coverage   64.16%   64.15%   -0.01%     
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  Files         888      888              
  Lines       53465    53469       +4     
  Branches     6596     6598       +2     
==========================================
- Hits        34304    34303       -1     
+ Misses      17651    17649       -2     
- Partials     1510     1517       +7     

[giohappy]

@mattiagiupponi the calculated box is wrong, as you can see from the thumbnail of this layer for Italy.

I also verified the extent coordinates reported inside the API response and they are actually wrong (consistent with the thumbnail area)

[kikislater]

@mattiagiupponi @giohappy thanks !