[oadp-1.3] OADP-3038 imagestream: region auto discovery

[openshift-cherrypick-robot]

This is an automated cherry-pick of #223

/assign kaovilai

[openshift-ci[bot]]

@openshift-cherrypick-robot: all tests passed!

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[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kaovilai, openshift-cherrypick-robot, weshayutin

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/openshift/openshift-velero-plugin/blob/oadp-1.3/OWNERS)~~ [kaovilai] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[weshayutin]

/lgtm