Rhumb line polygon triangulation creates too many triangles at pole

[Sandcastle example](https://cesiumjs.org/Cesium/Build/Apps/Sandcastle/index.html#c=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)

This example has one polygon at the south pole. It never displays because the worker which is creating the polygonGeometry ends up creating so many triangles that it exceeds system memory.

This only occurs when using rhumb lines. It loads with geodesics (though there are visual artifacts due to a separate issue)

Start with the linked Sandcastle example and trace the worker that creates the polygonGeometry for the south-pole polygon. Compare the rhumb-line and geodesic paths while investigating why rhumb-line triangulation produces excessive triangles. Done means the example loads without exhausting system memory and the polygon is triangulated with a reasonable number of triangles.

Written by the indexing model from the issue text.