Disallow EES users from access with ci_job_token

There was a bug, as a negation was missing. This has been added now, so
the feature should be good to merge now. 😄

Also includes minor style fixes

lib/api/jobs.rb

@@ -248,7 +248,7 @@ module API
       end
 
       def check_cross_project_pipelines_feature!
-        not_found!('Project') if job_token_authentication? && @project.feature_available?(:cross_project_pipelines)
+        not_found!('Project') if job_token_authentication? && !@project.feature_available?(:cross_project_pipelines)
       end
     end
   end

spec/requests/api/helpers_spec.rb

@@ -209,7 +209,7 @@ describe API::Helpers do
       let(:route_authentication_setting) { { job_token_allowed: true } }
 
       before do
-        allow_any_instance_of(API::Helpers).to receive(:doorkeeper_guard).and_return(nil)
+        allow_any_instance_of(described_class).to receive(:doorkeeper_guard).and_return(nil)
       end
 
       it "returns nil for an invalid token" do

spec/requests/api/jobs_spec.rb

@@ -17,8 +17,10 @@ describe API::Jobs do
   let(:api_user) { user }
   let(:reporter) { create(:project_member, :reporter, project: project).user }
   let(:guest) { create(:project_member, :guest, project: project).user }
+  let(:cross_project_pipeline_enabled) { true }
 
   before do
+    stub_licensed_features(cross_project_pipelines: cross_project_pipeline_enabled)
     project.add_developer(user)
   end
 
@@ -261,6 +263,15 @@ describe API::Jobs do
           expect(response).to have_http_status(404)
         end
       end
+
+      context 'feature is disabled for EES' do
+        let(:api_user) { user }
+        let(:cross_project_pipeline_enabled) { false }
+
+        it 'disallows access to the artifacts' do
+          expect(response).to have_http_status(404)
+        end
+      end
     end
   end
 
@@ -380,7 +391,7 @@ describe API::Jobs do
           get api("/projects/#{project.id}/jobs/artifacts/master/download"), job: job.name, job_token: job.token
         end
 
-        context 'when user is eporter' do
+        context 'when user is reporter' do
           it_behaves_like 'a valid file'
         end