Remove the compat SQL plugin names (QMYSQL3, QOCI8, QODBC3, QPSQL7) since they are not needed and just confuse the user [ChangeLog][QtSql] The compat plugin names QMYSQL3, QOCI8, QODBC3 and QPSQL7 are no longer available. Change-Id: I6d88f449ef3e18881a6970fb374ba0ab074ef302 Reviewed-by: Andy Shaw <andy.shaw@qt.io>