Fix valid_raw_connection check

[rporrasluc]

When upgrading to Rails 7.1, I observed that the client_connection was nil sometimes. It was found out that this is caused by @raw_connection being used instead of valid_raw_connection. We are using respond_to? without a second parameter but the method valid_raw_connection is private.

pry(#<ActiveRecord::ConnectionAdapters::VitessMysql2Adapter>)> self.class
=> ActiveRecord::ConnectionAdapters::VitessMysql2Adapter
pry(#<ActiveRecord::ConnectionAdapters::VitessMysql2Adapter>)> ::Rails.version
=> "7.1.2"
pry(#<ActiveRecord::ConnectionAdapters::VitessMysql2Adapter>)> respond_to?(:valid_raw_connection)
=> false
pry(#<ActiveRecord::ConnectionAdapters::VitessMysql2Adapter>)> respond_to?(:valid_raw_connection, true)
=> true

[adrianna-chang-shopify]

Thanks!