Auto merge of #25073 - servo:moar, r=jdm
Auto merge of #25073 - servo:moar, r=jdm

Increase parallelism in macOS WPT testing

… now that remaining dual-core workers have been upgraded to quad-cores.

Also reduces the number of WPT chunks since per-task overhead becomes more siginificant when tasks are becoming shorter.

DominoTree/servo,KiChjang/servo,splav/servo,DominoTree/servo,DominoTree/servo,KiChjang/servo,KiChjang/servo,splav/servo,splav/servo,DominoTree/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo,DominoTree/servo,KiChjang/servo,DominoTree/servo,splav/servo,DominoTree/servo,KiChjang/servo,splav/servo,DominoTree/servo,KiChjang/servo,splav/servo,KiChjang/servo,splav/servo,splav/servo,DominoTree/servo,splav/servo,DominoTree/servo,splav/servo