Don't translate debug level logs in nova.objects

Our translation policy
(https://wiki.openstack.org/wiki/LoggingStandards#Log_Translation) calls
for not translating debug level logs. This is to help prioritize log
translation. Furthermore translation has a performance overhead, even if
the log isn't used (since nova doesn't support lazy translation yet).

Change-Id: I8bdc66c0711539b373884dc35a84ee8143e6de67
Merge "Don't translate debug level logs in nova.objects"