Change in keep alive entry logging level
Keep alive entries are used to prevent skipped updates from being evaluated multiple times in fractional replication. If a large number of updates is skipped, these entries can be updated very frequently. Also, each entry is tested to see if it already exists before the update, so that only unique entries are created.
This test was previously logged at the `Fatal` level, which caused error logs to be filled with unnecessary messages that could not be filtered out. This update changes the logging level for keep alive entries from `Fatal` to `Replication debugging` (`8192`), and the entries can now be filtered out.