Update Rake spec
Update Rake spec

Use new spec helper methods to track and fetch the created transaction.

Also use `to_h` to fetch the transaction data from the extension rather
than expecting method calls, which are more fragile, especially without
using `and_call_original` on them.

appsignal/appsignal-ruby,appsignal/appsignal-ruby,appsignal/appsignal-ruby,appsignal/appsignal-ruby