Adapt thinking sphinx callback syntax

Thinking Sphinx v5.0 introduces explicit callbacks. Since we
are using the real time indices, we already have explicit
callbacks set. But at the same time, a new syntax for the
callback got introduced with:
-> pat/thinking-sphinx#1175
The old way is still supported, but in the changelogs it
is recommended to adapt the new style right away.

src/api/app/models/attrib.rb

@@ -18,17 +18,6 @@ class Attrib < ApplicationRecord
   accepts_nested_attributes_for :values, allow_destroy: true
   accepts_nested_attributes_for :issues, allow_destroy: true
 
-  #### Callbacks macros: before_save, after_save, etc.
-  after_save ThinkingSphinx::RealTime.callback_for(
-    :package, [:package]
-  ), if: -> { package_id_previously_changed? }
-
-  after_save ThinkingSphinx::RealTime.callback_for(
-    :project, [:project]
-  ), if: -> { project_id_previously_changed? }
-
-  #### Scopes (first the default_scope macro if is used)
-
   #### Validations macros
   validates_associated :values
   validates_associated :issues
@@ -43,6 +32,7 @@ class Attrib < ApplicationRecord
            :validate_allowed_values_for_attrib_type
 
   after_commit :write_container_attributes, on: [:create, :destroy, :update]
+  after_save :populate_to_sphinx
 
   #### Class methods using self. (public and then private)
   def self.find_by_container_and_fullname(container, fullname)
@@ -149,6 +139,19 @@ def validate_allowed_values_for_attrib_type
   def write_container_attributes
     container.write_attributes if container && !container.destroyed?
   end
+
+  def populate_to_sphinx
+    return unless package_id_previously_changed? || project_id_previously_changed?
+
+    define_sphinx_callback(:package, [:package]) if package_id_previously_changed?
+    define_sphinx_callback(:project, [:project]) if project_id_previously_changed?
+  end
+
+  def define_sphinx_callback(reference, path = [])
+    ThinkingSphinx::RealTime::Callbacks::RealTimeCallbacks.new(
+      reference, path
+    ).after_save(self)
+  end
 end
 
 # == Schema Information

src/api/app/models/package_issue.rb

@@ -7,13 +7,8 @@ class PackageIssue < ApplicationRecord
     joins('LEFT JOIN package_kinds ON package_kinds.package_id = package_issues.package_id').where('package_kinds.kind = "patchinfo"')
   }
 
-  after_save ThinkingSphinx::RealTime.callback_for(
-    :package, [:package]
-  )
-
-  after_save ThinkingSphinx::RealTime.callback_for(
-    :project, [:package, :project]
-  )
+  ThinkingSphinx::Callbacks.append(self, :package, behaviours: [:real_time], path: [:package])
+  ThinkingSphinx::Callbacks.append(self, :project, behaviours: [:real_time], path: [:package, :project])
 
   def self.sync_relations(package, issues)
     retries = 10