UB sanitizer: most TwostageGaussSeidel_functor ctors do not set forward_sweep field

[cwpearson]

An example failure here: https://github.com/kokkos/kokkos-kernels/actions/runs/11695504241/job/32571033270

I'm not 100% sure this is actually the problem, but I think it is: this causes the implicitly-defined copy-ctor for this (called internally by Kokkos in e.g. parallel_for) to initialize this bool field from whatever happens to be in memory, which is usually not technically a valid boolean value (e.g. 157).

In Trilinos/packages/kokkos-kernels/sparse/impl/KokkosSparse_twostage_gauss_seidel_impl.hpp

[cwpearson]

Fixed in #2420