Fix Qt-RangeLoopDetach: iteration over QMap::keys()

A loop that iterates a map over QMap::keys() and then accesses the
elements via operator[] can be more efficiently replaced with
QMap::asKeyValueRange().

Amends e8cadf8f88128758725ef7498ed7164751095832.
QMap::asKeyValueRange() is available since Qt 6.4, so we can pick the
change to all active branches.

Axivion-Id: qt_Add-ons_qtremoteobjects_dev_linux:SV333
Task-number: QTBUG-144772
Pick-to: 6.12 6.11 6.8
Change-Id: Idf19ceb35784cd062dc591264b03c9097c189744
Reviewed-by: Tatiana Borisova <tatiana.borisova@qt.io>