Remove .rubocop_revert_ignores.txt and backfill_integrations_type_new

This speeds up RuboCop file lookups because it has to match ~380 files
less.

It also removes BackfillIntegrationsTypeNew which was part of
.rubocop_revert_ignores.txt, caused RuboCop offenses but is not used
since 2023.

.rubocop.yml

@@ -46,10 +46,6 @@ AllCops:
     - 'spec/support/*.git/**/*'  # e.g. spec/support/gitlab-git-test.git
     # projects_controller.rb is used for testing LLM response and is very sensitive to whitespaces.
     - 'ee/spec/fixtures/llm/projects_controller.rb'
-    # Adding this specifically for a large revert: !118368
-    <% File.readlines('.rubocop_revert_ignores.txt').map(&:chomp).each do |f| %>
-    - '<%= f %>'
-    <% end %>
   # Use absolute path to avoid orphan directories with changed workspace root.
   CacheRootDirectory: <%= Dir.getwd %>/tmp
   MaxFilesInCache: 1_000_000

lib/gitlab/background_migration/backfill_integrations_type_new.rb

-# frozen_string_literal: true
-
-module Gitlab
-  module BackgroundMigration
-    # Backfills the new `integrations.type_new` column, which contains
-    # the real class name, rather than the legacy class name in `type`
-    # which is mapped via `Gitlab::Integrations::StiType`.
-    class BackfillIntegrationsTypeNew
-      include Gitlab::Database::DynamicModelHelpers
-
-      def perform(start_id, stop_id, batch_table, batch_column, sub_batch_size, pause_ms)
-        parent_batch_relation = define_batchable_model(batch_table, connection: connection)
-          .where(batch_column => start_id..stop_id)
-
-        parent_batch_relation.each_batch(column: batch_column, of: sub_batch_size) do |sub_batch|
-          process_sub_batch(sub_batch)
-
-          sleep(pause_ms * 0.001) if pause_ms > 0
-        end
-      end
-
-      private
-
-      def connection
-        ApplicationRecord.connection
-      end
-
-      def process_sub_batch(sub_batch)
-        # Extract the start/stop IDs from the current sub-batch
-        sub_start_id, sub_stop_id = sub_batch.pick(Arel.sql('MIN(id), MAX(id)'))
-
-        # This matches the mapping from the INSERT trigger added in
-        # db/migrate/20210721135638_add_triggers_to_integrations_type_new.rb
-        connection.execute(<<~SQL)
-          WITH mapping(old_type, new_type) AS (VALUES
-            ('AsanaService',                   'Integrations::Asana'),
-            ('AssemblaService',                'Integrations::Assembla'),
-            ('BambooService',                  'Integrations::Bamboo'),
-            ('BugzillaService',                'Integrations::Bugzilla'),
-            ('BuildkiteService',               'Integrations::Buildkite'),
-            ('CampfireService',                'Integrations::Campfire'),
-            ('ConfluenceService',              'Integrations::Confluence'),
-            ('CustomIssueTrackerService',      'Integrations::CustomIssueTracker'),
-            ('DatadogService',                 'Integrations::Datadog'),
-            ('DiscordService',                 'Integrations::Discord'),
-            ('DroneCiService',                 'Integrations::DroneCi'),
-            ('EmailsOnPushService',            'Integrations::EmailsOnPush'),
-            ('EwmService',                     'Integrations::Ewm'),
-            ('ExternalWikiService',            'Integrations::ExternalWiki'),
-            ('FlowdockService',                'Integrations::Flowdock'),
-            ('HangoutsChatService',            'Integrations::HangoutsChat'),
-            ('IrkerService',                   'Integrations::Irker'),
-            ('JenkinsService',                 'Integrations::Jenkins'),
-            ('JiraService',                    'Integrations::Jira'),
-            ('MattermostService',              'Integrations::Mattermost'),
-            ('MattermostSlashCommandsService', 'Integrations::MattermostSlashCommands'),
-            ('MicrosoftTeamsService',          'Integrations::MicrosoftTeams'),
-            ('MockCiService',                  'Integrations::MockCi'),
-            ('MockMonitoringService',          'Integrations::MockMonitoring'),
-            ('PackagistService',               'Integrations::Packagist'),
-            ('PipelinesEmailService',          'Integrations::PipelinesEmail'),
-            ('PivotaltrackerService',          'Integrations::Pivotaltracker'),
-            ('PrometheusService',              'Integrations::Prometheus'),
-            ('PushoverService',                'Integrations::Pushover'),
-            ('RedmineService',                 'Integrations::Redmine'),
-            ('SlackService',                   'Integrations::Slack'),
-            ('SlackSlashCommandsService',      'Integrations::SlackSlashCommands'),
-            ('TeamcityService',                'Integrations::Teamcity'),
-            ('UnifyCircuitService',            'Integrations::UnifyCircuit'),
-            ('WebexTeamsService',              'Integrations::WebexTeams'),
-            ('YoutrackService',                'Integrations::Youtrack'),
-
-            -- EE-only integrations
-            ('GithubService',                  'Integrations::Github'),
-            ('GitlabSlackApplicationService',  'Integrations::GitlabSlackApplication')
-          )
-
-          UPDATE integrations SET type_new = mapping.new_type
-          FROM mapping
-          WHERE integrations.id BETWEEN #{sub_start_id} AND #{sub_stop_id}
-            AND integrations.type = mapping.old_type
-        SQL
-      end
-    end
-  end
-end

spec/dot_gitlab_ci/rules_spec.rb

@@ -192,7 +192,6 @@
         '.mailmap',
         '.prettierignore',
         '.projections.json.example',
-        '.rubocop_revert_ignores.txt',
         '.solargraph.yml.example',
         '.solargraph.yml',
         '.test_license_encryption_key.pub',