Revert "Merge branch 'id-require-irb-for-initializer' into 'master' "

This reverts commit 81255b56, reversing
changes made to aff88028.

config/initializers/irb.rb

 # frozen_string_literal: true
 
-require 'irb'
-
 if Gitlab::Runtime.console?
   # Stop irb from writing a history file by default.
   module IrbNoHistory