Use `:empty_project` where possible in policy specs

spec/policies/issue_policy_spec.rb

@@ -5,7 +5,7 @@ describe IssuePolicy, models: true do
 
   describe '#rules' do
     context 'using a regular issue' do
-      let(:project) { create(:project, :public) }
+      let(:project) { create(:empty_project, :public) }
       let(:issue) { create(:issue, project: project) }
       let(:policies) { described_class.abilities(user, issue).to_set }
 

spec/policies/project_policy_spec.rb

@@ -74,7 +74,7 @@ describe ProjectPolicy, models: true do
   end
 
   it 'does not include the read_issue permission when the issue author is not a member of the private project' do
-    project = create(:project, :private)
+    project = create(:empty_project, :private)
     issue   = create(:issue, project: project)
     user    = issue.author