AthenaPoolMultiTest+IOVDbSvc: Remove references to CxxUtils/make_unique.h.

Remove unused references to obsolete header CxxUtils/make_unique.h.

This merge request affects 2 packages:

• AtlasTest/DatabaseTest/AthenaPoolMultiTest
• Database/IOVDbSvc

Adding @ssnyder as watcher

added Database Test master review-pending-level-1 labels

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-26804-2019-09-26-02-35
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 3593]

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 1522c654

added sweep:ignore label