Cleanup QSqlTableModelTest:
- use pmf QSignalSpy ctor
- use QCOMPARE/QCOMPARE_GE instead QVERIFY where possible
- properly close additional databases so temporary folders created for
sqlite can be deleted on exit
Pick-to: 6.9 6.8
Change-Id: I84e8960b81128c141a0e2cd6d03837c9b5ac6652
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>