Add missing argument to DeploymentService#predefined_variables

What does this MR do?

In development MockDeploymentService is configured https://gitlab.com/gitlab-org/gitlab-ce/blob/3a2abc1d/lib/api/services.rb#L726 - but calls to Project#deployment_variables always fail with:

     ArgumentError:
       wrong number of arguments (given 1, expected 0)
     # ./app/models/project_services/deployment_service.rb:14:in `predefined_variables'
     # ./app/models/project.rb:1797:in `deployment_variables'

This MR adds the missing argument.

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer