fix: retain observed equations after `structural_simplify` of `SDESystem`#3244

ChrisRackauckas merged 1 commit intoSciML:masterSciML/ModelingToolkit.jl:masterfrom

AayushSabharwal:as/sde-observed-eqsAayushSabharwal/ModelingToolkit.jl:as/sde-observed-eqsCopy head branch name to clipboard