fix: only solve parameter initialization for `NonlinearSystem`#3345

ChrisRackauckas merged 2 commits intoSciML:masterSciML/ModelingToolkit.jl:masterfrom

AayushSabharwal:as/nlsys-init-hotfixAayushSabharwal/ModelingToolkit.jl:as/nlsys-init-hotfixCopy head branch name to clipboard