Handle invalid selectors properly

[liggitt]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Many controllers and client listers assume we cannot encounter invalid selectors in persisted objects because they are validated. #99139 reported that the label selector validation is incomplete, and invalid values can be persisted.

This PR:

1. removes comments that invalid selectors are impossible
2. makes printers handle invalid selectors (so that listing deployments doesn't short-circuit if one of them has an invalid selector)
3. makes controllers/client listers that iterate over objects finding ones whose selectors match a specific set of labels skip objects with invalid selectors

Fixes handling of objects with invalid selectors

[liggitt]

/assign @deads2k

[fedebongio]

/triage accepted
thank you Jordan!

[brianpursley]

How about these? Should they also continue instead of return?

kubernetes/pkg/controller/clusterroleaggregation/clusterroleaggregation_controller.go

Lines 100 to 103 in 3f0b6d3

	runtimeLabelSelector, err := metav1.LabelSelectorAsSelector(&selector)
	if err != nil {
	return err
	}

kubernetes/pkg/scheduler/framework/plugins/podtopologyspread/common.go

Lines 73 to 76 in 09b2e8f

	selector, err := metav1.LabelSelectorAsSelector(c.LabelSelector)
	if err != nil {
	return nil, err
	}

[liggitt]

How about these? Should they also continue instead of return?

no, both of those represent an object containing multiple selectors... it's reasonable to require all selectors in the object to be valid for the object to function correctly

[deads2k]

Not that I think anyone was really looking in the past, but as a side-effect of this, some messages will no longer be in the log about the failures.

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: brianpursley, deads2k, liggitt

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Needs approval from an approver in each of these files:

• pkg/controller/deployment/OWNERS [deads2k,liggitt]
• pkg/controller/replicaset/OWNERS [deads2k,liggitt]
• pkg/controller/volume/persistentvolume/OWNERS [deads2k,liggitt]
• pkg/printers/OWNERS [brianpursley,deads2k,liggitt]
• pkg/registry/OWNERS [deads2k,liggitt]
• pkg/scheduler/OWNERS [liggitt]
• staging/src/k8s.io/client-go/OWNERS [deads2k,liggitt]

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