Mirror pods for static pods may not be created immediately during node startup
because either the node is not registered or node informer is not synced.
They will be created eventually when static pods are resynced (every 1-1.5 minutes).
However, during this delay of 1-1.5 mins, kube-scheduler might overcommit resources
to the node and eventually cause kubelet to reject pods with
OutOfCPU/OutOfMemory/OutOfPods error.
To ensure kube-scheduler is aware of static pod resource usage faster,
mirror pods are created as soon as the node registers.
The two are not coupled except accidentally. Separate them and
update callsites. This will reduce the scope of PodManager interface
to make exposing the pod worker cleaner.
There is only one caller and both sets of data are part of the
resync operation between kubelet's desired state and the actual
state of the pod workers. Reduces the size of the interface so
that it is easier to create another pod manager.
