fix: get rid of /dev/ in containers

`enableFakechroot = true` somehow triggered the inclusion of `/dev`.

Some fake chroots included `/dev/kvm` with different permissions,
so the produced container was not the same.

As this fake chroot is not needed anymore with using `--chroot` for `gramine-sgx-sign`,
it can be turned off.

Signed-off-by: Harald Hoyer <harald@matterlabs.dev>

overlays/nixsgxLib/default.nix

@@ -211,7 +211,6 @@ final: _:
                   inherit fromImage;
 
                   includeStorePaths = false;
-                  enableFakechroot = true;
                   extraCommands = (mkNixStore contents) + ''
                     (
                       set -e