Fix Rails/SaveBang offenses for spec/controllers/

What does this MR do and why?

This MR aims to solve the issue #220040 (closed)

File Change

• .rubocop_todo/rails/save_bang.yml
• spec/controllers/abuse_reports_controller_spec.rb
• spec/controllers/boards/issues_controller_spec.rb
• spec/controllers/sent_notifications_controller_spec.rb
• spec/controllers/sessions_controller_spec.rb

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.