[9.x] Allow choosing tables to truncate

[emargareten]

Currently when using DatabaseTruncation trait, there is no option to choose which tables should be truncated, I can either exclude all other tables in the $exceptTables array or it will go through all tables and attempt to truncate (which can be slow for databases with a lot of tables).

With this PR we can choose the tables for truncation by defining a $tablesToTruncate property.

class AuthenticationTest extends DuskTestCase
{
    use DatabaseTruncation;

    /**
     * Indicates which tables should be truncated.
     *
     * @var array
     */
    protected $tablesToTruncate = ['users'];

    //...
}