OWLS-93960 - NPE fix in PodDisruptionBudgetHelper

[ankedia]

The change to use label selectors when listing the PodDisruptionBudgets to filter out PDBs not created by the operator and PDBs for other domains. Modified the createNonOperatorPodDisruptionBudget method in the DomainProcessorTest to not add cluster-name and domain-uid labels and added a new unit test.

[russgold]

This is described as an NPE fix. What unit test reproduces the NPE, and how did you fix it?
I added new unit test whenMakeRightExecuted_ignoreNonOperatorPodDisruptionBudgets in DomainProcessorTest which reproduces the NPE. It's fixed by making sure that we don't try to add PDBs that don't have weblogic.clusterName or weblogic.createdByOperator=true label to DomainPrecenseInfo.