Fixes logging_sample.conf

Logging conf sample did not contain any loggers
except 'root'. This configuration did not allow
to operate internal logs of magnetodb service.

Closes-bug: #1382223
Closes-bug: #1381983
Change-Id: Ic644bad58015348c057c5f3d6b55f21346daccf1
Merge "Fixes logging_sample.conf"