CE-235: Switch to using mocked nfs server

Switch to using a custom vagrant box instead of e3-share-lab.

In general, the change was the (relatively minimal) change required to use a vagrant image that carries only base 7.0.6.1/4.0.0 and 7.0.7/5.0.0. This does mean that the playbook drops support for 7.0.5/3.4.1 - however, the only way that this impacts anything is the use of env.sh, so I think it counts as a safe bet.

There were some redundant IOCs, which I have at least in part removed, although I have not done a thorough investigation into them as this role should be deprecated.

Note further that some st.cmd files loaded random modules (fug, magnetps) for no particular reason; these were not being tested at all, so they were removed from the st.cmd files.

Currently the vagrant image is 1.2GB in size. It should be made smaller, but I spent about half a day trying to figure out how the :swear: one does that, and I could not figure it out. If you have better ideas than me, the actual image should be closer to 600 MB (300 MB per EPICS base installation), which would be nice to speed things up somewhat.