storage/db/dbtest: fix -cloud after refactoring

Change-Id: I7bd1ed03127830d6530415d77263ee8b0155a2c4
Reviewed-on: https://go-review.googlesource.com/37230
Run-TryBot: Quentin Smith <quentin@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
1 file changed