LUClusterVerifyGroup: Localize virtual file paths

The check for file consistency didn't properly handle virtual paths
in case of a virtual cluster. This didn't cause any breakage as in
a standard virtual cluster setup with only one node all files are
visible for every node.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>