fix: outgoing vertical coordinate should be 'height' in meters using zGridCenter

[hkershaw-brown]

Description:

mpas, observation vertical conversion was using zGridFace rather than zGridCenter

Following the call tree, using oncenters always

convert_vertical_obs
  -> convert_vert_distrib
     case (VERTISHEIGHT)
     -> find_vert_indices
        -> find_vert_level(oncenters = true)
           case (VERTEIGHT)
             if (oncenters)
             -> find_height_bounds(zGridCenter)

Fixes issue

fixes #524

Types of changes

• [x] 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)
• [ ] Documentation update

Documentation changes needed?

• [ ] My change requires a change to the documentation.
  • [ ] I have updated the documentation accordingly.

Tests

Please describe any tests you ran to verify your changes.

Skipped the early return so an obs with VERTISHEIGHT gets converted to VERTISHEIGHT. https://github.com/NCAR/DART/compare/main...hkershaw-brown:DART:bug_524_reproducer see https://github.com/NCAR/DART/issues/524#issuecomment-2447818389 for results.

Checklist for merging

• [ ] Updated changelog entry
• [ ] Documentation updated
• [ ] Update conf.py

Checklist for release

• [ ] Merge into main
• [ ] Create release from the main branch with appropriate tag
• [ ] Delete feature-branch

Testing Datasets

• [x] Dataset needed for testing available upon request
• [ ] Dataset download instructions included
• [ ] No dataset needed

You can grab my one obs test from /glade/derecho/scratch/hkershaw/DART/Bugs/bug_524/runs_524