Fix override operator image

[lampajr]

Fixes https://github.com/opendatahub-io/model-registry-operator/issues/24

Description

Makes the operator image correcly overridable using make deploy IMG=<...> script.

The issue is here: $(KUSTOMIZE) edit set image controller=${IMG} where controller is not the actual image in manager.yaml, and as per my understanding the kustomize edit should have the following structure:

$(KUSTOMIZE) edit set image ${CURRENT_IMG}=${NEW_IMG}:${NEW_TAG}

Therefore replacing controller with the actual image quay.io/opendatahub/model-registry-operator should do the trick.

How Has This Been Tested?

1. Run make deploy IMG=quay.io/opendatahub/model-registry-operator:main-4c04ff7
2. Describe the operator pod: k describe pod/model-registry-operator-controller-manager-<...> -n model-registry-operator-system
3. Normal Pulling 56s kubelet Pulling image "quay.io/opendatahub/model-registry-operator:main-4c04ff7"

Alternatively:

1. Run cd config/manager && kustomize edit set image quay.io/opendatahub/model-registry-operator=quay.io/opendatahub/model-registry-operator:main-4c04ff7
2. config/manager/kustomization.yaml should contain the following changes:

   apiVersion: kustomize.config.k8s.io/v1beta1
   kind: Kustomization
   images:
   - name: quay.io/opendatahub/model-registry-operator
   newName: quay.io/opendatahub/model-registry-operator
   newTag: main-4c04ff7

3. Issue kustomize build . or kustomize build config/manager depending if you are in the target directory or in the root.
4. Check the generated output contains :main-4c04ff7 version of the operator image:

   ...
         value: "false"
       image: quay.io/opendatahub/model-registry-operator:main-4c04ff7
       livenessProbe:
         httpGet:
           path: /healthz
           port: 8081
   ...

Merge criteria:

• [x] The commits and have meaningful messages; the author will squash them after approval or will ask to merge with squash.
• [x] Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• [x] The developer has manually tested the changes and verified that the changes work

[lampajr]

I think line image: controller as part of https://github.com/opendatahub-io/model-registry-operator/pull/38 will do the same, it changes the manager.yaml container image to a placeholder controller that can be replaced during the deploy.

So I think we can close this PR :)