classic: Reenable overview

Since we disabled the overview in the classic session, gnome-shell
switched to a horizontal workspace layout and replaced the activities
button with an indicator.

Those are big enough changes to reevaluate the decision, so remove
the delta with the regular session and turn it back on.

This reverts commit 82d2011061.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell-extensions/-/merge_requests/287>

data/classic.json.in

@@ -1,10 +1,9 @@
 {
     "parentMode": "user",
     "colorScheme": "force-light",
-    "hasOverview": false,
     "showWelcomeDialog": false,
     "enabledExtensions": [@CLASSIC_EXTENSIONS@],
-    "panel": { "left": [],
+    "panel": { "left": ["activities"],
                "center": [],
                "right": ["a11y", "keyboard", "dateMenu", "quickSettings"]
              }