Fix open_transactions_baseline to check the base class

What does this MR do and why?

Fix open_transactions_baseline to check the base class

We are querying the number of open transactions which is per connection, so we have to do the same for the open_transactions_baseline.

This fixes tests that test code for inside_transaction?. Without this fix, in test we get:

project.class.inside_transaction?
=> true

With this fix:

project.class.inside_transaction?
=> false

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