Model: Add left join to relations

RedundancyGroup -> DependencyEdge
DependencyEdge -> DependencyNode

The DependecyNodeSummary requires left joins to summarise all available rows,
while the redundancy group joins DependencyEdge and DependencyNode as inner joins, which leads to false positives.

library/Icingadb/Model/DependencyEdge.php

@@ -62,8 +62,11 @@ public function createRelations(Relations $relations): void
 
         // "from" and "to" are only necessary for sub-query filters.
         $relations->belongsTo('from', DependencyNode::class)
-            ->setCandidateKey('from_node_id');
+            ->setCandidateKey('from_node_id')
+            ->setJoinType('LEFT');
+
         $relations->belongsTo('to', DependencyNode::class)
-            ->setCandidateKey('to_node_id');
+            ->setCandidateKey('to_node_id')
+            ->setJoinType('LEFT');
     }
 }

library/Icingadb/Model/RedundancyGroup.php

@@ -65,10 +65,13 @@ public function createRelations(Relations $relations): void
         $relations->belongsToMany('from', DependencyEdge::class)
             ->setTargetCandidateKey('from_node_id')
             ->setTargetForeignKey('id')
-            ->through(DependencyNode::class);
+            ->through(DependencyNode::class)
+            ->setJoinType('LEFT');
+
         $relations->belongsToMany('to', DependencyEdge::class)
             ->setTargetCandidateKey('to_node_id')
             ->setTargetForeignKey('id')
-            ->through(DependencyNode::class);
+            ->through(DependencyNode::class)
+            ->setJoinType('LEFT');
     }
 }