SilverStripe\MSSQL\MSSQLDatabase::supportsTransactions
Transactions will work with FreeTDS, but not entirely with sqlsrv driver on Windows with MARS enabled.
TODO: - after the test fails with open transaction, the transaction should be rolled back, otherwise other tests will break claiming that transaction is still open. - figure out SAVEPOINTS - READ ONLY transactions
Signature
protected function supportsTransactions()