Ensure that DeletionTimestamp exists before patching the finalizers

[YCShen1010]

Ticket:
https://github.ibm.com/IBMPrivateCloud/roadmap/issues/61273
https://github.ibm.com/IBMPrivateCloud/roadmap/issues/61040

Issue description

In the AllNamespace/SingleNamespace migration path, NSS NamespaceScope resources failed to be deleted automatically during the initial run. However, upon restarting the CS pod, they will eventually be removed

Enhancement

• Adding a check to get the DeletionTimestamp in the PollImmediate function to address the timing issue where the deletion timestamp might not be available immediately after deletion
• List all NSS resources again to ensure that the DeletionTimestamp exists in all the resources before patching the finalizers

How to verify

Test image: quay.io/yuchen_shen/cs_operator:nss_cleanup

1. Deploy v4 CS instance in AllNamespace Mode
2. Manually create some NamespaceScope resources under ibm-common-services ns
3. Before applying the image: restart CS pod(only once), those resources will not be deleted
   After applying the image: restart CS pod(only once), those resources will be deleted eventualy

[Daniel-Fan]

/lgtm

[ibm-ci-bot]

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This pull-request has been approved by: Daniel-Fan, YCShen1010

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