Disable image when disabled

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Previously, when phpcr was enabled, but image disabled, the executing will
fail because cmf_core.image_enabled did not exists.