Originally the classic session replaced `gnome-shell.desktop` with
`gnome-shell-classic.desktop` (to add the --mode=classic parameter)
and added `nautilus-classic.desktop` (to force on desktop icons).
Neither is the case anymore (and hasn't been for years): Nowadays the
only expected difference is the GNOME_SHELL_SESSION_MODE variable and
the DesktopNames field, which are both set from the session .desktop
file rather than the gnome-session session definition.
Any difference in the latter - like not starting the USBProtection
plugin and missing systemd user session support - are bugs. The
easiest way to avoid those in the future is by removing the obsolete
duplication that enables them, so do just that.
https://gitlab.gnome.org/GNOME/gnome-shell-extensions/-/merge_requests/126
9a78c7e4f4
