Tweak FactoryBot definition for clusters

Only create an associated project or group if there
were none already specified.

spec/factories/clusters/clusters.rb

@@ -12,7 +12,7 @@ FactoryBot.define do
       cluster_type { Clusters::Cluster.cluster_types[:project_type] }
 
       before(:create) do |cluster, evaluator|
-        cluster.projects << create(:project, :repository)
+        cluster.projects << create(:project, :repository) unless cluster.projects.present?
       end
     end
 
@@ -20,7 +20,7 @@ FactoryBot.define do
       cluster_type { Clusters::Cluster.cluster_types[:group_type] }
 
       before(:create) do |cluster, evalutor|
-        cluster.groups << create(:group)
+        cluster.groups << create(:group) unless cluster.groups.present?
       end
     end