Move EE code out of Gitlab::PathRegex

This moves all EE code out of Gitlab::PathRegex and into
EE::Gitlab::PathRegex.

ee/lib/ee/gitlab/path_regex.rb

+# frozen_string_literal: true
+
+module EE
+  module Gitlab
+    module PathRegex
+      extend ActiveSupport::Concern
+
+      class_methods do
+        def saml_callback_regex
+          @saml_callback_regex ||= %r(\A\/groups\/(?<group>#{full_namespace_route_regex})\/\-\/saml\/callback\z).freeze
+        end
+      end
+    end
+  end
+end

lib/gitlab/path_regex.rb

@@ -233,10 +233,6 @@ module Gitlab
       }x
     end
 
-    def saml_callback_regex
-      @saml_callback_regex ||= %r(\A\/groups\/(?<group>#{full_namespace_route_regex})\/\-\/saml\/callback\z).freeze
-    end
-
     private
 
     def single_line_regexp(regex)
@@ -246,3 +242,5 @@ module Gitlab
     end
   end
 end
+
+Gitlab::PathRegex.prepend(EE::Gitlab::PathRegex)