TBB implementation of `reduce_by_key` incompatible with `transform_output_iterator`

As part of NVIDIA/thrust#1805 I added a new test that combines `reduce_by_key` with `transform_output_iterator`. This fails to compile due to this line:

https://github.com/NVIDIA/thrust/blob/d641d63802d08c17bde9498677be300cb4277bdf/thrust/system/tbb/detail/reduce_by_key.inl#L329

I have disabled that test for the TBB backend using the Cmake macro `thrust_declare_test_restrictions()`. Once this issue is fixed that test should be enabled for TBB.