Update no-ee-check with rubocop recommendation.

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

scripts/no-ee-check

 #!/usr/bin/env ruby
-ee_path = File.join(File.expand_path(File.dirname(__FILE__)), '../ee')
-result = Dir.exist?(ee_path)
+ee_path = File.join(File.expand_path(__dir__), '../ee')
 
-if result
+if Dir.exist?(ee_path)
   puts 'The repository contains /ee directory. There should be no /ee directory in CE repo.'
   exit 1
 end