Fixed downtime check label colouring

The colours were incorrect: offline was green and online was red,
instead of the opposite.

lib/gitlab/downtime_check/message.rb

@@ -3,8 +3,8 @@ module Gitlab
     class Message
       attr_reader :path, :offline, :reason
 
-      OFFLINE = "\e[32moffline\e[0m"
-      ONLINE = "\e[31monline\e[0m"
+      OFFLINE = "\e[31moffline\e[0m"
+      ONLINE = "\e[32monline\e[0m"
 
       # path - The file path of the migration.
       # offline - When set to `true` the migration will require downtime.

spec/lib/gitlab/downtime_check/message_spec.rb

@@ -5,13 +5,13 @@ describe Gitlab::DowntimeCheck::Message do
     it 'returns an ANSI formatted String for an offline migration' do
       message = described_class.new('foo.rb', true, 'hello')
 
-      expect(message.to_s).to eq("[\e[32moffline\e[0m]: foo.rb: hello")
+      expect(message.to_s).to eq("[\e[31moffline\e[0m]: foo.rb: hello")
     end
 
     it 'returns an ANSI formatted String for an online migration' do
       message = described_class.new('foo.rb')
 
-      expect(message.to_s).to eq("[\e[31monline\e[0m]: foo.rb")
+      expect(message.to_s).to eq("[\e[32monline\e[0m]: foo.rb")
     end
   end
 end