test: Convert scheduler tests to integration tests

Signed-off-by: Lewis Marshall <lewis@lmars.net>
test: Use existing slugrunner image in SchedulerSuite

Signed-off-by: Lewis Marshall <lewis@lmars.net>
test: Add / Remove hosts via HTTP

Signed-off-by: Lewis Marshall <lewis@lmars.net>
test: Add some debug logging

Signed-off-by: Lewis Marshall <lewis@lmars.net>
test: Increase timeout for job events

Signed-off-by: Lewis Marshall <lewis@lmars.net>
controller: Unregister service on exit

Signed-off-by: Lewis Marshall <lewis@lmars.net>