Update ActiveRecord::Base.connection to use with_connection for Rails 7.2 compatibility

[caitmich]

Summary

In Rails 7.2, ActiveRecord::Base.connection behaviour has changed. It no longer raises an exception when there is no db, but it instantiates a connection instead. According to the Rails documentation, with_connection and lease_connection are the new alternatives

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Check List

• Added a CHANGELOG entry
• Added specs