btr_cur_instant_init_low(): If columns were instantly added and dropped,
then index->is_instant() might not hold even though the root page type
was FIL_PAGE_TYPE_INSTANT. MariaDB 10.3 must refuse to open such files,
because instant DROP COLUMN is not supported.

Also, refuse to open the table if the metadata record has
wrong info OR status bits. Previously, we only refused to open
if both bits were wrong.