Reduce the visibility of various public identifiers that are only used
within the scope of a package.
This was originally motivated by KEP-3685 in order to reduce the public
API surface and improve supportability.
The member variable `cpuRatiosByZone` should be accessed with the lock
acquired as it could be be updated by `SetNodes` concurrently.
Signed-off-by: Quan Tian <qtian@vmware.com>
Co-authored-by: Antonio Ojea <aojea@google.com>
