Collapse/uncollapse icons show during search even when not usable

[ShridharGoel]

Suppose you have a deck Science::Math::Algebra::Group

If you search for "Algebra", then the little icon on the left of the deck shows that "Science" is not collapsed, "Math" is collapsed, and "Algebra" is not collapsed.

The button on the left of "Algebra" will allow to indeed collapse on uncollapsed subdecks. The button on the left of "Science" and "Math" will be ignored.

We should remove the buttons whose actions are ignored. That is, "Science" and "Math" should not show any button to collapse/uncollapse.

Originally posted by @Arthur-Milchior in #18298 (review)

[gautambhetanabhotla]

Hi, I'd like to work on this issue. Could it be assigned to me?

[david-allison]

Sure