Add logic in service_controller to skip create/update
if finalizer from a different controller is found.
The newly added finalizer will be checked by other controllers
implementing ILB services to determine if a given service is
already being managed by service_controller.
Moved finalizer check into cloudprovider code.
added unit test to verify new finalizer.
Modified existing unit test to create a fake service so that
attach/remove finalizer step can be tested.
A transient issue might occur that causes an error to be returned by
InstanceID(). When this is ignored, the external cloud provider taint
will be removed and neither AddCloudNode() nor UpdateCloudNode() will
try to set a provider ID in the future.
By returning the error we can ensure that the external cloud provider
taint is not removed prematurely, allowing the operation to be retried
(until the provider ID can be set).
Preserve support for external cloud providers that do not use IDs by
continuing if a NotImplemented error is returned, making a distinction
between lack of support for provider IDs and an actual error.
Introduce pair of unit tests that show a provider ID will eventually
be set if an error is returned, unless that error is a NotImplemented,
in which case the external cloud provider taint will be removed.
The `recorder.PastEventf` method wasn't actually working as advertised.
It was supposed to accept a timestamp, which would be used when
generating the event. However, as the
[source code](https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/client-go/tools/record/event.go#L316)
shows, this `timestamp` was never actually used.
In other words, `PastEventf` is identical to `Eventf`.
We have two options: one would be to fix `PastEventf` so that it works
as advertised. The other would be to delete `PastEventf` and only
support `Eventf`.
Ultimately, I could only find one use of `PastEventf` in the code base,
so I propose we just delete `PastEventf` and convert all uses to
`Eventf`.
This adds a new EndpointSlice tracker to keep track of the expected resource versions of EndpointSlices associated with each Service managed by the EndpointSlice controller. This should prevent a potential race where a syncService call could happen with an incomplete view of EndpointSlices if additions or deletions hadn't fully propagated to the cache yet. Additionally, this ensures that external changes to EndpointSlices will be handled by the EndpointSlice controller.
