[KCollapsibleGroupBox] Respect style's widget animation duration
Query QStyle::SH_Widget_Animation_Duration style hint.
QTimeLine requires a duration > 0, so use 1 [ms] to make
the animation as fast as possible when disabled.
BUG: 397103
FIXED-IN: 5.51.0
Reviewed by: ngraham, elvisangelaccio
Differential Revision: https://phabricator.kde.org/D15611