These files are required to get Nix in PATH in existing multi-user installs using
the legacy installer. We really could use some tests.
Cc: https://git.lix.systems/lix-project/lix/issues/33
This partially reverts commit 93cc063344.
Fixes: https://git.lix.systems/lix-project/lix/issues/173
Change-Id: Iafb55280596732670a432f604b897f48562868e4