[murano] Need to upload dependency image as public if user mark imported apps as public

Steps to reproduce:
1) Log in web UI as an admin user of some tenant
2) Navigate to Murano > Manage > Package Definitions
3) Import some app (from app storage ) that has an image as a dependency
4) Navigate to Project > Compute> Images, wait until image will be uploaded and notice that public=No
5) Log out from this tenant and log as admin user from another tenant
6) Navigate to Murano > Manage > Package Definitions - user will see all public apps
7) Navigate to Project > Compute> Images - user won't see dependency image that is needed for uploaded earlier public app

Expected result:
Image should be public too, otherwise in some cases user has to make some 'extra' manipulations to reach successful deployment of some apps.
For example, part of murano apps (by the current moment) have hardcoded image's name and user from another tenant (who didn't upload package) has to upload image to his tenant with 'hardcoded' name, otherwise deployment of murano env with its app will fail with Validation error

Upstream bug: https://bugs.launchpad.net/murano/+bug/1466448