This change is to promote local storage capacity isolation feature to GA
At the same time, to allow rootless system disable this feature due to
unable to get root fs, this change introduced a new kubelet config
"localStorageCapacityIsolation". By default it is set to true. For
rootless systems, they can set this configuration to false to disable
the feature. Once it is set, user cannot set ephemeral-storage
request/limit because capacity and allocatable will not be set.
Change-Id: I48a52e737c6a09e9131454db6ad31247b56c000a