Prepend EE::Gitlab::Regex into Gitlab::Regex

This ensures that we modify Gitlab::Regex using EE specific modules the
same way as we do with other modules/classes.

ee/lib/ee/gitlab/regex.rb

@@ -3,6 +3,9 @@
 module EE
   module Gitlab
     module Regex
+      extend ActiveSupport::Concern
+
+      class_methods do
         def environment_scope_regex_chars
           "#{environment_name_regex_chars}\\*"
         end
@@ -41,4 +44,5 @@ module EE
         end
       end
     end
+  end
 end

lib/gitlab/regex.rb

@@ -3,7 +3,6 @@
 module Gitlab
   module Regex
     extend self
-    extend EE::Gitlab::Regex # rubocop: disable Cop/InjectEnterpriseEditionModule
 
     def namespace_name_regex
       @namespace_name_regex ||= /\A[\p{Alnum}\p{Pd}_\. ]*\z/.freeze
@@ -108,3 +107,5 @@ module Gitlab
     end
   end
 end
+
+Gitlab::Regex.prepend(EE::Gitlab::Regex)