workspace: Fix set last_active_center_pane error

[CharlesChen0823]

Fix an bug set last_active_center_pane error.

Release Notes:

• N/A

[SomeoneToIgnore]

Again, a PR with zero context.

Which bug? How to reproduce this so people can test that you've fixed it?

Let's try again.

[CharlesChen0823]

emmm, with no context, because IMO, there only three line in this function, and this logic is straightforward.

    fn set_active_pane(&mut self, pane: &View<Pane>, cx: &mut ViewContext<Self>) {
+     self.last_active_center_pane = Some(self.active_pane.downgrade());
        self.active_pane = pane.clone();
        self.active_item_path_changed(cx);
-      self.last_active_center_pane = Some(pane.downgrade());

    }

set last_active_center_pane with same with active_pane?

I found this problem, when I try fix and edge case in pr #22563

@SomeoneToIgnore

[SomeoneToIgnore]

And while altering this "straightforward logic", 4 multiplayer tests have failed:
https://github.com/zed-industries/zed/actions/runs/12594612720/job/35102417600

so, I do not think it's that simple.

[SomeoneToIgnore]

Here's an example of a "trivial" change that's well-described: #22608

While I do not insist you writing that much, 0 elaboration, repeated, coupled with failing tests, is repulsive.