Upgrades fail if optimizer_adjust_secondary_key_costs is set

When Monty has introduced optimizer_adjust_secondary_key_costs,it was an integer.

He has also added a dummy variant of it into 11.4. All possible values were accepted but ignored.
The goal was that if one has

optimizer_adjust_secondary_key_costs=...

in their my.cnf, they could upgrade and the new server would not fail to start.

Then, optimizer_adjust_secondary_key_costs type was changed to set.
However, in 11.4+, the dummy implementation was not adjusted accordingly. Its type is still INT,

so, one attempting to upgrade now will get an error:

[3:52 PM]2026-04-30 15:49:04 0 [ERROR] ./mysqld: Error while setting value 'fix_innodb_cardinality,fix_reuse_range_for_ref' to 'optimizer_adjust_secondary_key_costs'[3:52 PM]