Refactor handleNotifications + solve bug

[mavaras]

Description

Refactors handleNotifications and solves a bug that was causing an issue when adding/updating/deleting notifications in a IR resource previously created with no notifications within it.

How has this been tested?

Whole functionality tested by deploying the operator to an Openshift cluster and using a test Quay organization to play with ImageRepository's notifications by testing all the functional workflows.

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JIRA: ISV-5058

[openshift-ci]

Hi @mavaras. Thanks for your PR.

I'm waiting for a konflux-ci member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

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-sigs/prow repository.

[MartinBasti]

Can you please add description also to commit, not just PR

[mmorhun]

/ok-to-test

[mavaras]

/test image-controller-e2e

[mmorhun]

/test image-controller-e2e