Remove tightvncserver from zLinux JCK machines

[sxa]

tightvncserver has a tendancy to segfault on startup on the zLinux machines we have. The machines also have vnc4server which starts up without problems. The default /usr/bin/vncserver is pointing to /etc/alternatives/vncserver which points to /usr/bin/tightvncerver so by default running vncserver causes a crash. We could use update-alternatives but removing the tightvncserver package and leaving vnc4server as the default seems like a better approach

[karianna]

Tagging with ansible as well since I assume it'll need to get removed from there as well.