Remove the meanwhile unused deprecated loading state API

src/calendarbase.cpp

@@ -650,10 +650,5 @@ void CalendarBase::endBatchAdding()
     KCalendarCore::MemoryCalendar::endBatchAdding();
 }
 
-bool CalendarBase::isLoaded() const
-{
-    return !isLoading();
-}
-
 #include "moc_calendarbase.cpp"
 #include "moc_calendarbase_p.cpp"

src/calendarbase.h

@@ -191,12 +191,6 @@ public:
      */
     bool modifyIncidence(const KCalendarCore::Incidence::Ptr &newIncidence);
 
-    /**
-     * Returns if the calendar already finished loading.
-     * Base class returns true.
-     */
-    [[deprecated("use isLoading() instead")]] bool isLoaded() const;
-
 Q_SIGNALS:
     /**
      * This signal is emitted when an incidence is created in akonadi through