[tests] Fix TrinoDialect.has_schema arguments

[john-bodley]

Description

This is where type enforcement would be really helpful. For the SQLAlchemy dialect the has_schema method was being passed the SQLAlchemy engine as opposed to the corresponding connection per here. Both objects have an execute(...) method which is why the tests worked, however I thought it was prudent to make make sure the callers used the correct arguments.

Non-technical explanation

Release notes

(x) This is not user-visible or docs only and no release notes are required. ( ) Release notes are required, please propose a release note for me. ( ) Release notes are required, with the following suggested text:

* Fix some things. ({issue}`issuenumber`)