TestS3GuardTool hangs/fails when offline: it's an IT test

If you try to run aws tests while offline, TestS3GuardTool hangs for some minutes before eventually failing; a superclass is trying to create an FS instance.

Even if the db is local, a remote object store is expected to exist. If none is defined the test is skipped. But if one is declared, then it must be reachable.

Proposed: s/TestS3GuardTool/r/ITestS3GuardTool/