Log the reson for returning 1 in the post-create event

[mzidek-gh]

Returning 1 in the post-create event usually means that we do not want to create the problem directory and report the bug, but it is not clear from the logs:

-- Logs begin at Thu 2020-12-03 10:33:05 CET. --
gen 27 08:51:30 localhost.localdomain abrt-server[12523]: 'post-create' on '/var/spool/abrt/ccpp-2021-01-27-08:51:29.648817-11689' exited with 1
gen 27 08:51:30 localhost.localdomain abrt-server[12523]: Deleting problem directory '/var/spool/abrt/ccpp-2021-01-27-08:51:29.648817-11689'

We should log a message with the reason for returning 1 in post-create in the default config file.