Update Rajagopal model to reduce logging about ForceVelocityCurve

[carmichaelong]

Follow up from opensim-org/opensim-core#2790

Model on SimTK (and likely downstream models) explicitly set tags concentric_slope_at_vmax and eccentric_slope_at_vmax as 0.0. Should update to 0.125 and 0.75 respectively based on log messages.