Fixes #25558 - better error on cv publish repo conflict

app/models/katello/repository.rb

@@ -96,7 +96,10 @@ class Repository < Katello::Model
 
     validates_with Validators::ContainerImageNameValidator, :attributes => :container_repository_name, :allow_blank => false, :if => :docker?
     validates :pulp_id, :presence => true, :uniqueness => true, :if => proc { |r| r.name.present? }
-    validates :container_repository_name, :uniqueness => true, :if => :docker?
+    validates :container_repository_name, :if => :docker?, :uniqueness => {message: ->(object, _data) do
+      _("for repository '%{name}' is not unique and cannot be created in '%{env}'. Its Container Repository Name (%{container_name}) conflicts with an existing repository.  Consider changing the Lifecycle Environment's Registry Name Pattern to something more specific.") %
+          {name: object.name, container_name: object.container_repository_name, :env => object.environment.name}
+    end}
 
     before_validation :set_pulp_id
     before_validation :set_container_repository_name, :if => :docker?