Don't use 'test' db for mysql since it's reserved.

This db name is reserved and used by mysql installations. This can cause
conflicts when trying to populate our own 'test' database on mysql.

@clytwynec @jzoldak @feanil @e0d

This ought to solve it for mysql 5.6 builds.

I also undo the no-harm change in 3f7d0f242b2dafd4d24261b6f9577b28abc4bc2e