Remove SparseArrays legacy code (#50637)

(cherry picked from commit c57d33a)

Author: dkarrasch

stdlib/LinearAlgebra/src/adjtrans.jl

@@ -64,21 +64,6 @@ end
 Adjoint(A) = Adjoint{Base.promote_op(adjoint,eltype(A)),typeof(A)}(A)
 Transpose(A) = Transpose{Base.promote_op(transpose,eltype(A)),typeof(A)}(A)
 
-# TODO: remove, is already replaced by wrapperop
-"""
-    adj_or_trans(::AbstractArray) -> adjoint|transpose|identity
-    adj_or_trans(::Type{<:AbstractArray}) -> adjoint|transpose|identity
-Return [`adjoint`](@ref) from an `Adjoint` type or object and
-[`transpose`](@ref) from a `Transpose` type or object. Otherwise,
-return [`identity`](@ref). Note that `Adjoint` and `Transpose` have
-to be the outer-most wrapper object for a non-`identity` function to be
-returned.
-"""
-adj_or_trans(::T) where {T<:AbstractArray} = adj_or_trans(T)
-adj_or_trans(::Type{<:AbstractArray}) = identity
-adj_or_trans(::Type{<:Adjoint}) = adjoint
-adj_or_trans(::Type{<:Transpose}) = transpose
-
 """
     inplace_adj_or_trans(::AbstractArray) -> adjoint!|transpose!|copyto!
     inplace_adj_or_trans(::Type{<:AbstractArray}) -> adjoint!|transpose!|copyto!

stdlib/LinearAlgebra/src/triangular.jl

@@ -671,12 +671,6 @@ fillstored!(A::UnitUpperTriangular, x) = (fillband!(A.data, x, 1, size(A,2)-1);
 # BlasFloat routines #
 ######################
 
-# legacy stuff, to be removed
-_multrimat!(C, A, B) = _trimul!(C, A, B)
-_mulmattri!(C, A, B) = _trimul!(C, A, B)
-_uconvert_copyto!(c, b, oA) = (c .= Ref(oA) .\ b)
-_uconvert_copyto!(c::AbstractArray{T}, b::AbstractArray{T}, _) where {T} = copyto!(c, b)
-
 # which triangle to use of the underlying data
 uplo_char(::UpperOrUnitUpperTriangular) = 'U'
 uplo_char(::LowerOrUnitLowerTriangular) = 'L'