Tabs in side panel in agents window are sized strangely

Testing https://github.com/microsoft/vscode/issues/329417

### Shrink

### Fit

This may be "by design", but based on the reading of the setting description, I don't expect there to be a difference between the "fit" and "shrink" when space is unlimited. Historically, editor tabs had space for the X, so hovering didn't hide some of the text. That no longer seems to be the case which I'm divided on, but the new tabs seem to change between fit and shrink when the window is large enough to use fit sizing.