[L2] fix basis order for non-local FE
In order to obtain the order of the basis, the L2 operator directly accesses localBasis instead of using the FiniteElementSwitch, which fails in case of a non-local basis.
In order to obtain the order of the basis, the L2 operator directly accesses localBasis instead of using the FiniteElementSwitch, which fails in case of a non-local basis.