Don't try to load non-code QML area backgrounds, are broken ATM

The commit "Drop usage of Plasma Components" was only a WIP
0be9b1dc046e8cc040b9106dcf747638e3180a80
area_debug.qml & area_review.qml newer got needed follow-up fixes
for item usage.

Due to the errors the background already was blank for these areas,
thus do for now officially and so avoid confusing debug log.