fix(admin): properly update `savedGrapherJson`
fix(admin): properly update `savedGrapherJson`

Co-authored-by: Daniel Gavrilov <5cce5e7a7eb30ecd47c852f4c1ea0885c4ef15da@gmail.com>
owid/owid-grapher,owid/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,owid/owid-grapher,owid/owid-grapher,OurWorldInData/owid-grapher,owid/owid-grapher,OurWorldInData/owid-grapher