Further Clarified How VMDK Driver Creates Cinder Volume Directory

This change replaces Change Id8adb9b9 which was abandoned because subsequent amendments kept reasserting changes that should have been abandoned.

backport: none
Closes-Bug: #1265044

Change-Id: I1064ba2cbb274b445dfc9c4dd5a7fb5b6973d2d7
Merge "Further Clarified How VMDK Driver Creates Cinder Volume Directory"