Fix Qt-RangeLoopDetach Axivion warnings

- use std::as_const() where possible, and introduce an intermediate
  local const variable where it is not.

Axivion-Id: qt_Add-ons_qtmqtt_dev_linux:SV34
Axivion-Id: qt_Add-ons_qtmqtt_dev_linux:SV35
Axivion-Id: qt_Add-ons_qtmqtt_dev_linux:SV36
Axivion-Id: qt_Add-ons_qtmqtt_dev_linux:SV37
Pick-to: 6.12
Task-number: QTBUG-144762
Change-Id: I7b6d53116269007aca7d6f050b2abeb2515e9390
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>