Revert "Remove historic minergate trigger"

This reverts commit 471e2d42.

changelogs/unreleased/ab-remove-minergate-trigger.yml

----
-title: Remove historic minergate trigger (GitLab.com only)
-merge_request: 54910
-author:
-type: other

db/migrate/20210223105256_remove_minergate_trigger_on_git_lab_com.rb

-# frozen_string_literal: true
-
-class RemoveMinergateTriggerOnGitLabCom < ActiveRecord::Migration[6.0]
-  include Gitlab::Database::MigrationHelpers
-
-  DOWNTIME = false
-
-  disable_ddl_transaction!
-
-  def up
-    return unless Gitlab.com?
-
-    with_lock_retries do
-      execute <<~SQL
-        DROP TRIGGER IF EXISTS ci_builds_block_minergate ON ci_builds;
-      SQL
-    end
-
-    execute <<~SQL
-      DROP FUNCTION IF EXISTS make_build_to_be_stuck_with_lock_version();
-      DROP FUNCTION IF EXISTS make_build_to_be_stuck();
-    SQL
-  end
-
-  def down
-    # no-op
-  end
-end

db/schema_migrations/20210223105256

-5fa0e89f9d7715309f6fd9808a07c34bcca0d556a2a4a2841f419b3279db8759
\ No newline at end of file