Don't show events bubble under GNOME Shell calendar, if calendar app is not present in system
When GNOME Calendar is not installed, it's redundant to show the events bubble under GNOME Shell calendar. Obviously there are "No Events", if there is no way for user to create events. This should follow same logic as weather and clocks bubbles: when the apps are not present, no bubbles are shown.
GNOME Shell 3.37.90, Fedora Branched (33), no extensions.