monitoring: test: check: disable custom plugins win32
monitoring: test: check: disable custom plugins win32

custom plugins don't work on windows and it is low priority, disable
tests for now.

kaustavha/rackspace-monitoring-agent,cp16net/virgo-base,virgo-agent-toolkit/rackspace-monitoring-agent,cp16net/virgo-base,AlphaStaxLLC/rackspace-monitoring-agent,cp16net/virgo-base,kaustavha/rackspace-monitoring-agent,cp16net/virgo-base,AlphaStaxLLC/rackspace-monitoring-agent,virgo-agent-toolkit/rackspace-monitoring-agent,christopherjwang/rackspace-monitoring-agent,christopherjwang/rackspace-monitoring-agent,cp16net/virgo-base