Require irb gem for an initializer

What does this MR do and why?

Require irb gem for an initializer. Rails 7.1 start explicitly adding this gem as a dependency.

• https://github.com/rails/rails/blob/v7.1.5.1/railties/railties.gemspec#L47
• https://github.com/rails/rails/blob/v7.0.8.7/railties/railties.gemspec#L47

We don't have it in Gemfile, so let's explicitly require it.

Related issue: gitlab-org/build/CNG!2242 (comment 2380333754)