Remove unneeded roles from linux node in windows tests

The linux node have extra roles (specifically agent) caused it to
execute a large number of tests that it doesn't need to. The linux
agents are tested in a different setup already. Removing the agent from
the linux node should also drastically reduce the runtime of the tests.
Merge pull request #476 from zaphod42/remove-linux-agent-from-windows

Remove unneeded roles from linux node in windows tests