[OM] Remove Ubuntu 16.04 Dependencies from OpsMgr tutorial

Update: Ubuntu 16.04 is EOL. Thus remove the instructions and mentions here: https://docs.mongodb.com/manual/tutorial/install-mongodb-enterprise-on-ubuntu-tarball/#install-mongodb-enterprise-edition

Ubuntu 16.04 is missing from this page (for enterprise dependencies to install) – and should be missing (see comments in this ticket).

https://docs.opsmanager.mongodb.com/current/tutorial/provisioning-prep/index.html#installing-mongodb-enterprise-dependencies 

I was able to find the information here :

https://docs.mongodb.com/manual/tutorial/install-mongodb-enterprise-on-ubuntu-tarball/#install-mongodb-enterprise-edition