Improve selection of require packages. bnc#895070. bnc#896178. bnc#896185.

this will make future extension hard, as you need to stock more exception. Having similar style like in vnc_packages seems better for me:
```
def remote_x11_packages
  packages = REMOTE_X11_BASE_PACKAGES.dup
  packages << "yast2-x11" if Mode.autoinst
  packages
end
```