Rename too long migration filename

changelogs/unreleased/mwaw-rename_to_long_migration_filename.yml

+---
+title: Rename too long migration filename to address gem packaging limitations.
+merge_request:
+author:
+type: fixed

db/migrate/20200116051619_drop_activate_prometheus_services_for_shared_cluster_applications_background_migration.rb → db/migrate/20200116051619_drop_background_migration_jobs.rb

 # frozen_string_literal: true
 
-class DropActivatePrometheusServicesForSharedClusterApplicationsBackgroundMigration < ActiveRecord::Migration[5.2]
+class DropBackgroundMigrationJobs < ActiveRecord::Migration[5.2]
   include Gitlab::Database::MigrationHelpers
 
   DOWNTIME = false

spec/migrations/drop_activate_prometheus_services_for_shared_cluster_applications_background_migration_spec.rb → spec/migrations/drop_background_migration_jobs_spec.rb

 # frozen_string_literal: true
 
 require 'spec_helper'
-require Rails.root.join('db', 'migrate', '20200116051619_drop_activate_prometheus_services_for_shared_cluster_applications_background_migration.rb')
+require Rails.root.join('db', 'migrate', '20200116051619_drop_background_migration_jobs.rb')
 
-describe DropActivatePrometheusServicesForSharedClusterApplicationsBackgroundMigration, :sidekiq, :redis, :migration, schema: 2020_01_16_051619 do
+describe DropBackgroundMigrationJobs, :sidekiq, :redis, :migration, schema: 2020_01_16_051619 do
   subject(:migration) { described_class.new }
 
   describe '#up' do