Update powellsg :nls variant to use @adjust_nvar_warn macro

Ensures consistent warning messages between :nlp and :nls variants,
showing both original and adjusted dimension values.

Author: arnavk23

src/ADNLPProblems/powellsg.jl

@@ -25,8 +25,9 @@ function powellsg(::Val{:nlp}; n::Int = default_nvar, type::Type{T} = Float64, k
 end
 
 function powellsg(::Val{:nls}; n::Int = default_nvar, type::Type{T} = Float64, kwargs...) where {T}
-  (n % 4 == 0) || @warn("powellsg: number of variables adjusted to be a multiple of 4")
+  n_orig = n
   n = 4 * max(1, div(n, 4))
+  @adjust_nvar_warn("powellsg", n_orig, n)
   function F!(r, x; n = length(x))
     @inbounds for j = 1:4:n
       r[j] = x[j] + 10 * x[j + 1]