In MySQL 8, redo log size calculation changed

[gordan-bobic]

In MySQL 8, there is a new setting:

innodb_redo_log_capacity

That is used instead of:

innodb_log_file_size x innodb_log_files_in_group

for determining total log size. This is a little confusing because the two old variables still have default values when they are not set (48MB x 2), but are not in used.

The new value should be used when available for the "InnoDB Log File Usage Hourly" graph.