643c1248b8
When equality constraints and built-in passive forces are not present, edge Jacobians are unused. This gives a 3x speedup in `mj_kinematics` in `floppy_flex` (from 0.2ms/step to 0.06ms/step). Changed the default options of `floppy_flex` to match those of `floppy` for a fair comparison. PiperOrigin-RevId: 575850622 Change-Id: I4c618536fd17ef930153bbd1f1da7d9e0e44abbe