fix: drop conv and campaign seq on account delete (#4256)

Conversation and campaign sequences persist in the database even after the related account is deleted. This PR adds an after_desttory callback on the account model that will delete the associated sequences.

Fixes: #4252

spec/models/account_spec.rb

@@ -30,4 +30,14 @@ RSpec.describe Account do
       expect(account.usage_limits).to eq({ agents: ChatwootApp.max_limit, inboxes: ChatwootApp.max_limit })
     end
   end
+
+  context 'when after_destroy is called' do
+    it 'conv_dpid_seq and camp_dpid_seq_ are deleted' do
+      account = create(:account)
+      query = "select * from information_schema.sequences where sequence_name in  ('camp_dpid_seq_#{account.id}', 'conv_dpid_seq_#{account.id}');"
+      expect(ActiveRecord::Base.connection.execute(query).count).to eq(2)
+      account.destroy
+      expect(ActiveRecord::Base.connection.execute(query).count).to eq(0)
+    end
+  end
 end