Change `has_many :organizations` on Group to `has_many :crm_organizations`

This is similar to the change we did in !118584 (merged).

We do not want clashes between the existing organization naming schema and the Organization we are trying to build for cells (https://docs.gitlab.com/ee/architecture/blueprints/cells/cells-feature-organizations.html) and hence this association

has_many :organizations

should be changed to

has_many :crm_organizations

Internal discussion on Slack