2.4.2: Add toggle to determine whether to set request.user.
Although setting the `request.user` during `process_view` worked to solve ARCH-1197 in ecommerce, it introduced an OOM bug in edx-platform. This introduces a temporary toggle using a Django Setting so that the fix can remain in ecommerce without affecting other IDAs like edx-platform. Once ARCH-1199 is complete and the issue is fixed, it is expected that this toggle will be removed. ARCH-1210