Switch ActsOnTaggable model's DB connection to ci database

We need to do two things:

1. Override the LB connection (which is based off the base class's LB)
1. Override the connection_specification_name for other Rails connection
methods that LB does not handle such as retrieve_connection

config/initializers/0_acts_as_taggable.rb → config/initializers/1_acts_as_taggable.rb

@@ -9,3 +9,9 @@ ActsAsTaggableOn.tags_counter = false
 # validate that counter cache is disabled
 raise "Counter cache is not disabled" if
     ActsAsTaggableOn::Tagging.reflections["tag"].options[:counter_cache]
+
+# Redirects retrieve_connection to use Ci::ApplicationRecord's connection
+[::ActsAsTaggableOn::Tag, ::ActsAsTaggableOn::Tagging].each do |model|
+  model.connection_specification_name = Ci::ApplicationRecord.connection_specification_name
+  model.singleton_class.delegate :connection, :sticking, to: '::Ci::ApplicationRecord'
+end

spec/models/acts_as_taggable_on/tag_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe ActsAsTaggableOn::Tag do
+  it 'has the same connection as Ci::ApplicationRecord' do
+    query = 'select current_database()'
+
+    expect(described_class.connection.execute(query).first).to eq(Ci::ApplicationRecord.connection.execute(query).first)
+    expect(described_class.retrieve_connection.execute(query).first).to eq(Ci::ApplicationRecord.retrieve_connection.execute(query).first)
+  end
+
+  it 'has the same sticking as Ci::ApplicationRecord' do
+    expect(described_class.sticking).to eq(Ci::ApplicationRecord.sticking)
+  end
+end

spec/models/acts_as_taggable_on/tagging_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe ActsAsTaggableOn::Tagging do
+  it 'has the same connection as Ci::ApplicationRecord' do
+    query = 'select current_database()'
+
+    expect(described_class.connection.execute(query).first).to eq(Ci::ApplicationRecord.connection.execute(query).first)
+    expect(described_class.retrieve_connection.execute(query).first).to eq(Ci::ApplicationRecord.retrieve_connection.execute(query).first)
+  end
+
+  it 'has the same sticking as Ci::ApplicationRecord' do
+    expect(described_class.sticking).to eq(Ci::ApplicationRecord.sticking)
+  end
+end