Add query for conf.sample oslo.db bug 1393559

There are multiple projects that hit this since they
are auto-generating and validating their config samples
in the gate, and it looks like they are already fixed
but we should classify the bug.

36 hits in 48 hours. Filtering on the gate queue to
avoid some non-integrated projects.

Change-Id: Ibe7ef55a2de52cacee77f5bcd0a136b7dc0b8e4e
Related-Bug: #1393559
Merge "Add query for conf.sample oslo.db bug 1393559"