Windows: Fixed `ROOT_DOCKER_DockerHealthStatusChange` test.
Windows: Fixed `ROOT_DOCKER_DockerHealthStatusChange` test.

The `ROOT_DOCKER_DockerHealthStatusChange` was broken if the test ran
in a drive other than `C:\`, since only `C:\` exists in the docker
container with the default settings. The test was changed to hardcode
the `C:\` drive on Windows.

Review: https://reviews.apache.org/r/67313/

Gilbert88/mesos,Gilbert88/mesos,abudnik/mesos,kaysoky/mesos,gsantovena/mesos,Gilbert88/mesos,kaysoky/mesos,jpeach/mesos,abudnik/mesos,dforsyth/mesos,reneploetz/mesos,kaysoky/mesos,chhsia0/mesos,andschwa/mesos,kaysoky/mesos,dforsyth/mesos,andschwa/mesos,andschwa/mesos,kaysoky/mesos,gsantovena/mesos,dforsyth/mesos,kaysoky/mesos,dforsyth/mesos,reneploetz/mesos,reneploetz/mesos,dforsyth/mesos,jpeach/mesos,Gilbert88/mesos,gsantovena/mesos,jpeach/mesos,andschwa/mesos,abudnik/mesos,andschwa/mesos,gsantovena/mesos,chhsia0/mesos,jpeach/mesos,abudnik/mesos,gsantovena/mesos,reneploetz/mesos,Gilbert88/mesos,chhsia0/mesos,chhsia0/mesos,andschwa/mesos,reneploetz/mesos,chhsia0/mesos,chhsia0/mesos,dforsyth/mesos,Gilbert88/mesos,reneploetz/mesos,kaysoky/mesos,gsantovena/mesos,andschwa/mesos,Gilbert88/mesos,reneploetz/mesos,jpeach/mesos,gsantovena/mesos,abudnik/mesos,chhsia0/mesos,abudnik/mesos,abudnik/mesos,jpeach/mesos,dforsyth/mesos,jpeach/mesos