[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.

for table, column in [
        ('transactions', 'tx_time'),
        ('tx_entity_actions', 'tx_uuid'),
        ('tx_relation_actions', 'tx_uuid')]:
    repo.system_source.create_index(session, table, column)

commit()