chore: Use "create!" and "save!" bang methods when not checking the result (#5358)

* Use "create!" when not checking for errors on the result
* Use "save!" when not checking the result

spec/workers/conversation_reply_email_worker_spec.rb

@@ -37,7 +37,7 @@ RSpec.describe ConversationReplyEmailWorker, type: :worker do
       end
 
       it 'calls ConversationSummaryMailer#reply_without_summary when last incoming message was from email' do
-        message.save
+        message.save!
         described_class.new.perform(1, message.id)
         expect(mailer).to have_received(:reply_without_summary)
       end