[slapos_cloud] fixup! add new catalog method to fetch item with aggregate or with child aggregate

put back `related_predecessor_but_with_different_title_than_catalog_title` which was removed by commit 85c7fb26

/reviewed-on nexedi/slapos.core!80

master/bt5/slapos_cloud/CatalogRelatedKeyTemplateItem/related_key_list.xml

@@ -2,4 +2,5 @@
  <key>causality_subscription_request_related_uid | category,catalog/uid/z_related_causality_subscription_request</key>
  <key>default_or_child_aggregate_reference | catalog,category,catalog/reference/z_related_default_or_child_aggregate</key>
  <key>default_or_child_aggregate_uid | catalog,category,catalog/uid/z_related_default_or_child_aggregate</key>
+ <key>related_predecessor_but_with_different_title_than_catalog_title | category,catalog/uid/z_related_predecessor_but_with_different_title_than_catalog_title</key>
 </key_list>
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