A quick proof of concept to improve performance of styles that use data-driven fill-color in combination with fill-antialias: false: avoid generating fill-outline-color paint buffers since they would duplicate fill-color (with notable GPU memory footprint on heavy layers like hillshade) but are not used in practice. Let's see if this makes a difference in benchmarks. Related: #10579

Launch Checklist

• briefly describe the changes in this PR
• write tests for all new functionality
• document any changes to public APIs
• post benchmark scores
• manually test the debug page
• tagged @mapbox/map-design-team @mapbox/static-apis if this PR includes style spec API or visual changes
• tagged @mapbox/gl-native if this PR includes shader changes or needs a native port
• apply changelog label ('bug', 'feature', 'docs', etc) or use the label 'skip changelog'
• add an entry inside this element for inclusion in the mapbox-gl-js changelog: <changelog>Improve performance for fill layers with data-driven color and antialias: false</changelog>