Fix a bug in the editor's handling of the
`multi_buffer::Event::ExcerptsRemoved` event, where the display map's
`folded_buffers` set was not updated according to the list of removed
buffer ids.
Since the `ProjectSearchView` now relies on the
`Editor.has_any_buffer_folded` method in order to decide the state of
the expand/collapse all excerpts button this could lead to a
bug where, after an initial project search, all excerpts would be
collapsed, and performing a new search would leave the button in a wrong
state, as all excerpts from the new search result would be expanded, but
the button would still consider that there were folded excerpts for the
buffers.
Closes#50521
Release Notes:
- Fixed bug in project search where collapsing a single buffer then
performing a new search in the same view, would break the
expand/collapse all button behavior