[test/querier] use the new connection api (part 1/3) In devtools/repotest, we provide a simple `.qexecute` with autocommit, and we use it (where possible) in unittest_querier. Note that the .session object is a real session, not the magic property found in CubicWebTC test classes.

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raise NotImplementedError("Cannot migrate such an old version. Use intermediate Cubiweb version (try 3.16.x)")