QA: Automate basic server testing

[zenmonkeykstop]

The default QA test plan includes a basic testing section that mostly checks server configuration. These tests are duplicated in the production testinfra tests, so with some work to get testinfra to use production settings where available (via install_files/ansible-base/group_vars/all/site-specific), it should be possible to reduce tester workload by removing Basic testing in favour of testinfra.