Decrese agent to log to INFO level after uid is received

Biggest part of agent logs is information about disks discovery
which is DEBUG level

Any changes with disks will be available in nailgun api log

Change-Id: Idecbb1a4b045ea126acd04b6164b93e9c1fb1d0f
Closes-Bug: 1393115
Merge "Decrese agent to log to INFO level after uid is received"