Restrict all KSandbox use to KCoreAddons 5.97
Other uses (and the include) of KSandbox are restricted to KCoreAddons 5.97, so do the same here so it compiles with earlier versions of KCoreAddons.
Other uses (and the include) of KSandbox are restricted to KCoreAddons 5.97, so do the same here so it compiles with earlier versions of KCoreAddons.