Remove ee-specific-lines-check script

**Why?**
This is no longer needed after the single codebase move

https://gitlab.com/gitlab-org/gitlab/issues/2952

scripts/ee-specific-lines-check

-#!/usr/bin/env ruby
-
-require_relative 'ee_specific_check/ee_specific_check'
-
-include EESpecificCheck # rubocop:disable Style/MixinUsage
-git_version
-
-base = find_compare_base
-
-current_numstat = updated_diff_numstat(base.ce_base, base.ee_base)
-updated_numstat = updated_diff_numstat(base.ce_head, base.ee_head)
-
-offenses = updated_numstat.select do |file, updated_delta|
-  current_delta = current_numstat[file]
-
-  more_lines = updated_delta > current_delta
-
-  more_lines &&
-    !WHITELIST.any? { |pattern| Dir.glob(pattern, File::FNM_DOTMATCH).include?(file) }
-end
-
-if offenses.empty?
-  say "🎉 All good, congrats! 🎉"
-else
-  puts
-
-  offenses.each do |(file, delta)|
-    puts "* 💥 #{file} has #{delta - current_numstat[file]} updated lines that differ between EE and CE! 💥"
-  end
-
-  say <<~MESSAGE
-    ℹ️ Make sure all lines in shared files have been updated in your backport merge request and the branch name includes #{minimal_ce_branch_name}.
-    ℹ️ Consider using an EE module to add the features you want.
-    ℹ️ See this for detail: https://docs.gitlab.com/ee/development/ee_features.html#ee-features-based-on-ce-features
-  MESSAGE
-end
-
-remove_remotes
-
-say "ℹ️ For more information on why, see https://gitlab.com/gitlab-org/gitlab/issues/2952"
-
-exit(offenses.size)