Additional feature flag check for EE::Project
The EE::Project module, which gets prepended into the Project model
overrides the feature_available? method and needs an additional
feature flag check.
Note that the test only verifies the negative condition. There are additional conditions required for the method to ultimately return true, but those are exercised thoroughly by existing tests.
See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4213#note_106858716