BUG get image logic

Description

OADP code is changed when sent to production, for example
https://github.com/openshift/oadp-operator/blob/fe0444c847f79a8a12d03f3d67208c552af12457/config/manager/manager.yaml#L39-L56
values are changed to production images.

But, these values are not changed
https://github.com/openshift/oadp-operator/blob/fe0444c847f79a8a12d03f3d67208c552af12457/pkg/common/common.go#L60-L69

Which means, in a production environment, all fallback from below functions, are wrong.
https://github.com/openshift/oadp-operator/blob/fe0444c847f79a8a12d03f3d67208c552af12457/controllers/velero.go#L514-L522

https://github.com/openshift/oadp-operator/blob/fe0444c847f79a8a12d03f3d67208c552af12457/pkg/credentials/credentials.go#L94-L152

How to reproduce

Install OADP operator from marketplace and change the value of one these environment variables to an empty string (or remove the environment variable). Create DPA that will use one of these images, without using unsupportedOverrides. OADP will try to use a non production image instead of a production one.

Related work for DPA when API version updates

Instead of having unsupportedOverrides field in DPA, could not we use these environment variables to change images used? Instead of a field in DPA, would need to change value in operator CSV.

Start by comparing the production image values in config/manager/manager.yaml with the fallback values in pkg/common/common.go. Trace the fallback paths in controllers/velero.go and pkg/credentials/credentials.go, then reproduce by removing an image environment variable and creating a DPA without unsupportedOverrides. Done means production deployments select production images when those variables are empty or absent.