🐛 Use defined scanner image also for container scan

[czunker]

When the MondooAuditConfig defiens a custom image, also use it for the container scan CronJob.

Fixes #887

[czunker]

Also tried it locally:

k get -n mondoo-operator mondooauditconfigs.k8s.mondoo.com mondoo-client -o yaml | grep -A3 image                                                                --
    image:
      name: nginx
      tag: 1.25-alpine

k get -n mondoo-operator cronjob.batch/mondoo-client-containers-scan -o yaml | grep image                                                                     
            image: nginx:1.25-alpine

[imilchev]

nice that we also have a test for this!