Possible memory leak in coinitService for CallMethod

[yusufozturk]

If oleutil.CallMethod returns error, which is very possible in a high WMI load situations, then we do not release "wmi" or "unknown" objects. Also we are not able to call ole.CoUninitialize() anymore.

[jesus-velez]

@yusufozturk based on https://github.com/influxdata/telegraf/issues/6807#issuecomment-590256733 would you know how to fix this? I am not a go programmer but willing to test.