Disable fog (opacity = 0) on globe with terrain elevation

[birkskyum]

Closes #4928

• The unsupported Fog/Horizon is isn't disabled properly on Globe with Terrain3D #4928

Towards

• [Feat] Support Terrain in Globe projection #4927

As mentioned here, the globe doesn't support Fog "calculateFogMatrix is not supported on globe projection":

maplibre-gl-js/src/geo/projection/globe_transform.ts

Line 682 in ef6e9ee

warnOnce('calculateFogMatrix is not supported on globe projection.');

Unfortunately, it's still trying to render it, which consistently breaks the map whenever the map is pitched just a bit.

This tiny PR simply set the opacity of the fog/horizon to 0 in globe+terrain mode. When the globe does support fog with terrain, this can easily be removed again:

• Fix terrain fog on globe #4924

Fog is still active on Terrain3D without Globe

With Globe - zoom level before mercator transition

Before

After - main branch

After - local branch

With Globe - high zoom, after transition to mercator

Before

After

Without Globe - Fog Still Works

Before/After

Launch Checklist

• Confirm your changes do not include backports from Mapbox projects (unless with compliant license) - if you are not sure about this, please ask!

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 90.45%. Comparing base (51a2efd) to head (d6899ef).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/render/program/terrain_program.ts	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4963      +/-   ##
==========================================
- Coverage   90.67%   90.45%   -0.23%     
==========================================
  Files         266      266              
  Lines       38163    38164       +1     
  Branches     3164     3254      +90     
==========================================
- Hits        34606    34521      -85     
- Misses       2611     2650      +39     
- Partials      946      993      +47     

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[HarelM]

Can you add a unit test to cover this issue somehow?

[birkskyum]

@HarelM , I've added a unit tests, and a render test that can be used to help validate a fix to the fog

• Fix terrain fog on globe #4924

[HarelM]

Overall approved, let me know if the file I commented on is needed.

[HarelM]

Please add a changelog entry.