Allow seamless upgrade despite ROW_FORMAT=COMPRESSED

In MDEV-23497, the configuration option innodb_read_only_compressed was introduced to giver users advance notice of a plan to remove ROW_FORMAT=COMPRESSED support for InnoDB.

The next step of this plan would have been to remove write support for ROW_FORMAT=COMPRESSED tables (MDEV-22367). Based on user feedback, this plan has been scrapped. Even though ROW_FORMAT=COMPRESSED is a dead end and causes some overhead for InnoDB data structures, we can live with that.

Now that we know that some users really want to keep using ROW_FORMAT=COMPRESSED, the previous default value of the parameter innodb_read_only_compressed=ON should be changed to OFF, to allow smooth upgrades to 10.6 and later versions, without requiring users to update any configuration file.