Merge pull request #37660 from adamemerson/wip-datalog-fix

cls/fifo: Switch use CLS_ERR for errors
rgw/fifo: Fix a few missed return value assignments
rgw/fifo: Add some error logging
rgw/fifo: Catch two instances journaling a new part
rgw/fifo: Use unique_ptr and explicit release for callbacks

Reviewed-by: J. Eric Ivancich <ivancich@redhat.com>