metadata_cubes test failure on macOS Debug build

See https://github.com/isce-framework/isce3/actions/runs/17449127890/job/49552033059

The testMetadataCubes unit test seems to be failing during ground-track velocity computation due to an out-of-bounds Eigen array access.

The relevant test output seems to be this:

journal: cube height: 2
journal:
 -- cube length: 250
 -- cube width: 250
journal: EPSG: 4326
journal: estimating the ground-track velocity using rdr2geo
look side: Left
running topo for height: 0
Assertion failed: (row >= 0 && row < rows() && col >= 0 && col < cols()), function operator(), file DenseCoeffsBase.h, line 119.
journal:
 -- DEM EPSG: 4326
 -- Output EPSG: 4326
journal:
 -- Processing block: 1 
 --   - line start: 0
 --   - line end  : 250
 --   - dopplers near mid far: 0 0 0 
journal: East limit may be insufficient for global height range
journal: South limit may be insufficient for global height range
journal:
 -- Actual DEM bounds used:
 -- Top Left: -97.9481 49.6583
 -- Bottom Right: -97.6831 49.3431 
 -- Spacing: 0.0002 -0.0002
 -- Dimensions: 1326 1577

Note that you must build in Debug mode to see this error, so that Eigen bounds checking is enabled.