shell/window-tracker: Exclude screen recorder window
The pipeline contains a GST plugin that pops up an unclosable zero-sized window.
Unfortunately we did not manage to come up with a proper fix in time, so for now explicitly exclude it from app tracking.
This does not address all issues (it still prevents the window's workspace from getting removed, even when it appears empty), but at least it avoids the most confusing effect by preventing the "app" from showing up in dash, alt-tab etc.