Remove ProjectAuthorization.roles_stats method

With the new logic for the users statistics the previously used
ProjectAuthorization.roles_stats is obsolete and can be removed.

ee/app/models/ee/project_authorization.rb

@@ -12,39 +12,6 @@ module EE
       def pluck_user_ids
         pluck(:user_id)
       end
-
-      # Get amount of users with highest role they have.
-      # If John is a developer in one project but maintainer in another he will be
-      # counted once as maintainer. This is needed to count users who don't use
-      # functionality available to higher roles only.
-      #
-      # Example of result:
-      #  [{"kind"=>"guest", "amount"=>"4"},
-      #  {"kind"=>"reporter", "amount"=>"6"},
-      #  {"kind"=>"developer", "amount"=>"10"},
-      #  {"kind"=>"maintainer", "amount"=>"9"},
-      #  {"kind"=>"owner", "amount"=>"1"}]
-      #
-      def roles_stats
-        connection.exec_query <<-EOF.strip_heredoc
-          SELECT CASE access_level
-            WHEN 10 THEN 'guest'
-            WHEN 20 THEN 'reporter'
-            WHEN 30 THEN 'developer'
-            WHEN 40 THEN 'maintainer'
-            WHEN 50 THEN 'owner'
-            ELSE 'unknown' END
-            AS kind,
-            count(*) AS amount
-          FROM (
-              SELECT user_id, max(access_level) AS access_level
-              FROM #{table_name}
-              GROUP BY user_id
-          ) access_per_user
-          GROUP BY access_level
-          ORDER BY access_level ASC;
-        EOF
-      end
     end
   end
 end

ee/spec/models/ee/project_authorization_spec.rb

@@ -3,36 +3,6 @@
 require 'spec_helper'
 
 describe ProjectAuthorization do
-  describe '.roles_stats' do
-    before do
-      project1 = create(:project_empty_repo)
-      project1.add_reporter(create(:user))
-
-      project2 = create(:project_empty_repo)
-      project2.add_developer(create(:user))
-
-      # Add same user as Reporter and Developer to different projects
-      # and expect it to be counted once for the stats
-      user = create(:user)
-      project1.add_reporter(user)
-      project2.add_developer(user)
-    end
-
-    subject { described_class.roles_stats.to_a }
-
-    it do
-      expect(amount_for_kind('reporter')).to eq(1)
-      expect(amount_for_kind('developer')).to eq(2)
-      expect(amount_for_kind('maintainer')).to eq(2)
-    end
-
-    def amount_for_kind(access_level)
-      subject.find do |row|
-        row['kind'] == access_level
-      end['amount'].to_i
-    end
-  end
-
   describe '.visible_to_user_and_access_level' do
     let(:user) { create(:user) }
     let(:project1) { create(:project) }