Update use cases for the mode parameter in PDOStatement::fetchAll()

[colshrapnel]

Currently, case 3 makes no sense (PDO::FETCH_COLUMN|PDO::FETCH_UNIQUE would result in error) and case 4 is misleading (describing rather vanilla PDO::FETCH_GROUP's behavior). I added vanilla PDO::FETCH_UNIQUE and PDO::FETCH_GROUP cases and fixed PDO::FETCH_GROUP|PDO::FETCH_COLUMN.

Also, how does one remove a comment?

• 88699 is bogus, they need PDO::FETCH_UNIQUE but using PDO::FETCH_GROUP
• 122299 same as above
• 115175 is bogus, PDO::FETCH_UNIQUE|PDO::FETCH_GROUP makes no sense and effectively just PDO::FETCH_UNIQUE