chore: Enable the new Rubocop rules (#7122)

fixes: https://linear.app/chatwoot/issue/CW-1574/renable-the-disabled-rubocop-rules

spec/finders/conversation_finder_spec.rb

@@ -1,6 +1,6 @@
 require 'rails_helper'
 
-describe ::ConversationFinder do
+describe ConversationFinder do
   subject(:conversation_finder) { described_class.new(user_1, params) }
 
   let!(:account) { create(:account) }

spec/finders/email_channel_finder_spec.rb

@@ -1,6 +1,6 @@
 require 'rails_helper'
 
-describe ::EmailChannelFinder do
+describe EmailChannelFinder do
   include ActionMailbox::TestHelper
   let!(:channel_email) { create(:channel_email) }
 

spec/finders/message_finder_spec.rb

@@ -1,6 +1,6 @@
 require 'rails_helper'
 
-describe ::MessageFinder do
+describe MessageFinder do
   subject(:message_finder) { described_class.new(conversation, params) }
 
   let!(:account) { create(:account) }