Avoid detach and copy from container


Don't use operator[] to access an element, and iterate over references
of strings.

Axivion-Id: qt_Add-ons_qtcharts_dev_linux:SV787
Axivion-Id: qt_Add-ons_qtcharts_dev_linux:SV800
Task-number: QTBUG-146050
Pick-to: 6.12
Change-Id: I6640d45c89763265cf31818481aa44695e866b53
Reviewed-by: Kwanghyo Park <kwanghyo.park@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
commit9186a84bdefe50bdb8b766313b153506d3a0d212
parent0b800affb3429d8f56e572827204d58c463f1d1b
authorVolker Hilsheimer <volker.hilsheimer@qt.io>
committerVolker Hilsheimer <volker.hilsheimer@qt.io>
commit timeThu, 18 Jun 2026 11:49:41 +0000