The `getDataUpload` function in the CSI PVC backup plugin was
previously making a cluster-scoped list query to retrieve DataUpload
CRs. In environments with strict minimum-privilege RBAC, this would
fail with forbidden errors.
This explicitly passes the backup namespace into the `ListOptions`
when calling `crClient.List`, correctly scoping the queries to the
backup's namespace. Unit tests have also been updated to ensure
cross-namespace queries are rejected appropriately.
Signed-off-by: Adam Zhang <adam.zhang@broadcom.com>