Workspace: Avoid unnecesary resets of the tabbox model
When the tabbox switcher is shown and any window is added or removed, its client model is fully reset, even if this window is not included in the model.
This can be a bit expensive and also produce small visual quirks on certain switchers, so let's check if the window affects the tabbox before resetting it.
BUG: 466660 FIXED-IN: 6.0
Just tested over the 5.27 branch, but it should make no difference