Revert "fix: change fullscreen state when switching tab"

This reverts commit b89bf07d1e.

This turned out to be annoying when enabling fullscreen manually and then
switching through tabs.

qutebrowser/mainwindow/tabbedbrowser.py

@@ -926,7 +926,6 @@ class TabbedBrowser(QWidget):
                         .format(current_mode.name, mode_on_change))
         self._now_focused = tab
         self.current_tab_changed.emit(tab)
-        self.cur_fullscreen_requested.emit(tab.data.fullscreen)
         self.cur_search_match_changed.emit(tab.search.match)
         QTimer.singleShot(0, self._update_window_title)
         self._tab_insert_idx_left = self.widget.currentIndex()