fix: QnA list render slow issue

[zhixzhan]

Description

Previously, questions are all rendered, even rows are collapsed, expand is set question components 'hide'/'show'. That cause perf issue when QnA is large. benchmark from low performance laptop:

1. when table list first page ( top 10 QnA pairs ), questions amount more than 1000, scroll on list will feel 1s delay.
2. when questions amount less than 500, UX still feel smoothy.
3. when each pairs don't have much alternative questions, more than 10000 line qna file still smooth, UX works fine.

So the bottleneck is rendered too many hide question components in viewport. and the amount of QnA pairs will not cause perf issue.

Fix it by render only one question when row collapsed.

Task Item

close #4849

Screenshots

[coveralls]

Coverage decreased (-0.004%) to 54.461% when pulling 71a93b9 on zhixzhan/qnalist-perf-fix into abce2a7 on main.