Reduce CentralCapacityController workque depth by filtering allowed topologies in storage class

[yuxiang-he]

Is your feature request related to a problem?/Why is this needed

See onSCAddOrUpdate implementation in https://github.com/kubernetes-csi/external-provisioner/blob/v4.0.0/pkg/capacity/capacity.go#L378-L384

	segments := c.topologyInformer.List()

	c.capacitiesLock.Lock()
	defer c.capacitiesLock.Unlock()
	for _, segment := range segments {
		c.addWorkItem(segment, sc)
	}

Currently the capacity controller creates a workqueue item for every segment x storageClass combination, some of which are impossible.

Describe the solution you'd like in detail

Storage classes can specify allowed topologies https://kubernetes.io/docs/concepts/storage/storage-classes/#allowed-topologies so not all combinations of segment x storageClass are valid here. An example would be certain types of storage (and hence storage class) are only available in selected topology segments.

We can reduce potential workqueue cardinality by filtering out impossible segment x storageClass combinations. This allows quicker CSIStorageCapacity object updates.

Describe alternatives you've considered

Additional context

[yuxiang-he]

This is another issue discovered while investigating #1161

[pohly]

This makes sense to me.

/triage accepted
/help

[k8s-ci-robot]

@pohly:
This request has been marked as needing help from a contributor.

Guidelines

Please ensure that the issue body includes answers to the following questions:

• Why are we solving this issue?
• To address this issue, are there any code changes? If there are code changes, what needs to be done in the code and what places can the assignee treat as reference points?
• Does this issue have zero to low barrier of entry?
• How can the assignee reach out to you for help?

For more details on the requirements of such an issue, please see here and ensure that they are met.

If this request no longer meets these requirements, the label can be removed
by commenting with the /remove-help command.

In response to this:

This makes sense to me.

/triage accepted
/help

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.