Don't reset the fish_cursor_selection_mode in fish_default_key_bindings

As of the parent commit, __fish_vi_key_bindings_remove_handlers
should be working properly now, so this is no longer necessary That
function also cleans up other stuff like fish_cursor_end_mode, that
fish_default_key_bindings doesn't know anything about.

Also this fixes a spurious exit status of 4 in some scenarios.

share/functions/fish_default_key_bindings.fish

@@ -88,6 +88,4 @@ function fish_default_key_bindings -d "emacs-like key binds"
             # the following to tell a console to paste:
             $legacy_bind --preset $argv \e\x20ep fish_clipboard_paste
     end
-
-    set -e -g fish_cursor_selection_mode
 end