Don't translate debug level logs in nova.compute

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).

Continuation of Ie1068d2d2c7c37f27c62d0e4e5a64a1a504af9f5

Change-Id: Id6ed926df97fe31b4d553546818de5356e3a4cbb
Merge "Don't translate debug level logs in nova.compute"