Fix vulnerabilities API spec

This spec was failing because it assumed that the order returned
by the API would be the same from run to run. Fix this by
requesting enough per page so that we retrieve all possible
vulnerabilities.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/11411

ee/spec/requests/api/vulnerabilities_spec.rb

@@ -26,19 +26,17 @@ describe API::Vulnerabilities do
       end
 
       it 'returns all vulnerabilities' do
-        get api("/projects/#{project.id}/vulnerabilities", user)
+        get api("/projects/#{project.id}/vulnerabilities?per_page=40", user)
 
         expect(response).to have_gitlab_http_status(200)
         expect(response).to include_pagination_headers
         expect(response).to match_response_schema('vulnerabilities/occurrence_list', dir: 'ee')
 
         expect(response.headers['X-Total']).to eq('37')
-        expect(response.headers['X-Total-Pages']).to eql('2')
+        expect(response.headers['X-Total-Pages']).to eql('1')
 
-        expect(json_response.count).to eq 20
+        expect(json_response.count).to eq 37
         expect(json_response.map { |v| v['report_type'] }.uniq).to match_array %w[dependency_scanning sast]
-
-        expect(json_response.first['name']).to eq 'DoS by CPU exhaustion when using malicious SSL packets'
       end
 
       describe 'filtering' do