When we calculate statistic data from database, we print a debug
level log which says something like:
computed value coming from u'(<ceilometer.storage.impl_mongodb.Connection
object at 0x12345678>,)'
This message only indicates which type of database we are using,
nothing more. However the database type is specified by config file,
so this log is actually redundant.
Change-Id: Ia52f2d5f74509999097151e6906b4233214d74eb
Closes-Bug: #1459911
0d135b28d4